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Background: Treatment for hypertension improves cardiovascular outcomes. Frailty may be present in older people treated for hypertension, but associates with adverse drug effects, potentially including falls resulting in fractures. We aimed to determine the association between baseline frailty and fractures in patients initiated on antihypertensive treatment. Methods: We conducted a retrospective cohort study using United Kingdom primary care data, including new users of first-line antihypertensives aged 65 years or over. We reported degree of frailty (fit, mild, moderate, severe) at antihypertensive initiation using the Electronic Frailty Index. We examined the association of frailty with fractures using multivariable Poisson regression, and assessed for interaction between antihypertensive class and frailty. Results: Of 113,779 patients aged 65 years or over who initiated on first-line antihypertensives, 49,634 patients (44%) were mildly or more frail. Over 4.1 years mean follow-up, 6567 (5.8%) experienced a fracture, with 3832 (58%) of these fractures occurring in frail people. Among those with severe frailty, doubling of fracture risk was observed after antihypertensive initiation, compared with fit people [adjusted rate ratio 2.26, 95% confidence interval (CI) 1.93–2.65]. Secondary analyses indicate this pattern was replicated for hip and arm fractures, and strongest for spine fractures, and the association between different types of antihypertensives and fractures varied by frailty (p = 0.004), being lower in moderately frail users of renin-angiotensin blockers compared with calcium channel blockers [rate ratio 0.81, 95% CI 0.71–0.94]. Conclusions: Frailty is common among older patients initiating first-line antihypertensive treatment, and was associated with an increased fracture rate. Awareness of this is important to encourage clinicians to consider risk of falls and fractures when treating hypertension.

Introduction There is concern regarding adverse effects of antihypertensive treatment, including falls and subsequent fractures, especially hip fractures. As frailty is increasingly recognised as an important risk factor for adverse outcomes, we examined its relationship to fracture rates in older patients after starting antihypertensives. Methods Using the Clinical Practice Research Datalink (CPRD), we identified participants over 65-years old starting a first-line antihypertensive medication. Using deficits identified in CPRD we classified patient-level frailty as “Fit”, “Mild”, “Moderate” or “Severe” using the Electronic Frailty Index. We calculated the rate of fractures by frailty level and fracture site, and determined the rate ratio (RR) of first fracture by frailty level, adjusting for confounding, using multivariable poisson regression. We conducted sensitivity analyses to additionally adjust for ethnicity, deprivation, and bisphosphonate use. Results 44% of participants were classified as mildly frail or greater, but frail participants experienced 58% of all fractures, and 63% of hip fractures. The whole cohort showed a crude rate of 14.1 fractures/1000 person-years, with 4.5 hip fractures/1000 person-years. In severe frailty, this rises to 51.0 fractures/1000 person-years, and 17.7 hip fractures/1000 person-years. After adjustment for confounding, increasing frailty was associated with greater rate of any fracture, reaching RR 2.85 (95% confidence interval 2.43–3.33) for severe frailty versus fit. Results were unchanged in sensitivity analyses. Conclusions Frailty and fracture are both common in older participants who start antihypertensive medications. Increasing frailty was positively associated with increased rates of fracture. Clinicians need awareness of this relationship to consider fracture risk assessment and prevention in these patients.

Whilst many with SARS-CoV-2 infection have mild disease, managed in the community, individuals with cardiovascular risk factors experienced often more severe acute disease, requiring hospitalisation. Increasing concern has also developed over long symptom duration in many individuals, including the majority who managed acutely in the community. Risk factors for long symptom duration, including biological variables, are still poorly defined.We examine post-illness metabolomic and gut-microbiome profiles, in community-dwelling participants with SARS-CoV-2, ranging from asymptomatic illness to Post-COVID Syndrome, and participants with prolonged non-COVID-19 illnesses. We also assess a pre-established metabolomic biomarker score for its association with illness duration.We found an atherogenic-dyslipidaemic metabolic profile, and greater biomarker scores, associated with longer illness, both in individuals with and without SARS-CoV-2 infection. We found no association between illness duration and gut microbiome in convalescence.Findings highlight the potential role of cardiometabolic dysfunction to the experience of long illness duration, including after COVID-19.

BackgroundSelf-reported symptom studies rapidly increased our understanding of SARS-CoV-2 during the pandemic and enabled the monitoring of long-term effects of COVID-19 outside the hospital setting. It is now evident that post-COVID syndrome presents with heterogeneous profiles, which need characterisation to enable personalised care among the most affected survivors. This study describes post-COVID profiles, and how they relate to different viral variants and vaccination status.MethodsIn this prospective longitudinal cohort study, we analysed data from 336,652 subjects, with regular health reports through the Covid Symptom Study (CSS) smartphone application. These subjects had reported feeling physically normal for at least 30 days before testing positive for SARS-CoV-2. 9,323 individuals subsequently developed Long-COVID, defined as symptoms lasting longer than 28 days. 1,459 had post-COVID syndrome, defined as more than 12 weeks of symptoms. Clustering analysis of the time-series data was performed to identify distinct symptom profiles for post-COVID patients, across variants of SARS-CoV-2 and vaccination status at the time of infection. Clusters were then characterised based on symptom prevalence, duration, demography, and prior conditions (comorbidities).Using an independent testing sample with additional data (n=140), we investigated the impact of post-COVID symptom clusters on the lives of affected individuals.FindingsWe identified distinct profiles of symptoms for post-COVID syndrome within and across variants: four endotypes were identified for infections due to the wild-type variant; seven for the alpha variant; and five for delta. Across all variants, a cardiorespiratory cluster of symptoms was identified. A second cluster related to central neurological, and a third to cases with the most severe and debilitating multi-organ symptoms. Gastrointestinal symptoms clustered in no more than two specific phenotypes per viral variant. The three main clusters were confirmed in an independent testing sample, and their functional impact was assessed.InterpretationUnsupervised analysis identified different post-COVID profiles, characterised by differing symptom combinations, durations, and functional outcomes. Phenotypes were at least partially concordant with individuals’ reported experiences.Our classification may be useful to understand distinct mechanisms of the post-COVID syndrome, as well as subgroups of individuals at risk of prolonged debilitation.FundingUK Government Department of Health and Social Care, Chronic Disease Research Foundation, The Wellcome Trust, UK Engineering and Physical Sciences Research Council, UK Research and Innovation London Medical Imaging & Artificial Intelligence Centre for Value-Based Healthcare, UK National Institute for Health Research, UK Medical Research Council, British Heart Foundation and Alzheimer’s Society, and ZOE Limited, UK.Research in contextEvidence before this studyWe conducted a search in the PubMed Central database, with keywords: (“Long-COVID*” OR “post?covid*” OR “post?COVID*” OR postCOVID* OR postCovid*) AND (cluster* OR endotype* OR phenotype* OR sub?type* OR subtype).On 15 June 2022, 161 documents were identified, of which 24 either provided descriptions of sub-types or proposed phenotypes of Long-COVID or post-COVID syndrome(s). These included 16 studies attempting manual sub-grouping of phenotypes, 6 deployments of unsupervised methods for patient clustering and automatic semantic phenotyping (unsupervised k-means=2; random forest classification=1; other=2), and two reports of uncommon presentations of Long-COVID/post-COVID syndrome. Overall, two to eight symptom profiles (clusters) were identified, with three recurring clusters. A cardiopulmonary syndrome was the predominant observation, manifesting with exertional intolerance and dyspnoea (n=10), fatigue (n=8), autonomic dysfunction, tachycardia or palpitations (n=5), lung radiological abnormalities including fibrosis (n=2), and chest pain (n=1). A second common presentation consisted in persistent general autoimmune activation and proinflammatory state (n=2), comprising multi-organ mild sequelae (n=2), gastrointestinal symptoms (n=2), dermatological symptoms (n=2), and/or fever (n=1). A third syndrome was reported, with neurological or neuropsychiatric symptoms: brain fog or dizziness (n=2), poor memory or cognition (n=2), and other mental health issues including mood disorders (n=5), headache (n=2), central sensitization (n=1), paresthesia (n=1), autonomic dysfunction (n=1), fibromyalgia (n=2), and chronic pain or myalgias (n=6). Unsupervised clustering methods identified two to six different post-COVID phenotypes, mapping to the ones described above.14 further documents focused on possible causes and/or mechanisms of disease underlying one or more manifestations of Long-COVID or post-COVID and identifying immune response dysregulation as a potential common element. All the other documents were beyond the scope of this work.To our knowledge, there are no studies examining the symptom profile of post-COVID syndrome between different variants and vaccination status. Also, no studies reported the modelling of longitudinally collected symptoms, as time-series data, aiming at the characterisation of post-COVID syndrome.Added-value of this studyOur study aimed to identify symptom profiles for post-COVID syndrome across the dominant variants in 2020 and 2021, and across vaccination status at the time of infection, using a large sample with prospectively collected longitudinal self-reports of symptoms. For individuals developing 12 weeks or more of symptoms, we identified three main symptom profiles which were consistent across variants and by vaccination status, differing only in the ratio of individuals affected by each profile and symptom duration overall.Implications of all the available evidenceWe demonstrate the existence of different post-COVID syndromes, which share commonalities across SARS-CoV-2 variant types in both symptoms themselves and how they evolved through the illness. We describe subgroups of patients with specific post-COVID presentations which might reflect different underlying pathophysiological mechanisms. Given the time-series component, our study is relevant for post-COVID prognostication, indicating how long certain symptoms last. These insights could aid in the development of personalised diagnosis and treatment, as well as helping policymakers plan for the delivery of care for people living with post-COVID syndrome.

BACKGROUND: The SARS-CoV-2 variant of concern, omicron, appears to be less severe than delta. We aim to quantify the differences in symptom prevalence, risk of hospital admission, and symptom duration among the vaccinated population. METHODS: In this prospective longitudinal observational study, we collected data from participants who were self-reporting test results and symptoms in the ZOE COVID app (previously known as the COVID Symptoms Study App). Eligible participants were aged 16-99 years, based in the UK, with a body-mass index between 15 and 55 kg/m2, had received at least two doses of any SARS-CoV-2 vaccine, were symptomatic, and logged a positive symptomatic PCR or lateral flow result for SARS-CoV-2 during the study period. The primary outcome was the likelihood of developing a given symptom (of the 32 monitored in the app) or hospital admission within 7 days before or after the positive test in participants infected during omicron prevalence compared with those infected during delta prevalence. FINDINGS: Between June 1, 2021, and Jan 17, 2022, we identified 63 002 participants who tested positive for SARS-CoV-2 and reported symptoms in the ZOE app. These patients were matched 1:1 for age, sex, and vaccination dose, across two periods (June 1 to Nov 27, 2021, delta prevalent at >70%; n=4990, and Dec 20, 2021, to Jan 17, 2022, omicron prevalent at >70%; n=4990). Loss of smell was less common in participants infected during omicron prevalence than during delta prevalence (16·7% vs 52·7%, odds ratio [OR] 0·17; 95% CI 0·16-0·19, p

BackgroundThe Delta (B.1.617.2) variant became the predominant UK circulating SARS-CoV-2 strain in May 2021. How Delta infection compares with previous variants is unknown.MethodsThis prospective observational cohort study assessed symptomatic adults participating in the app-based COVID Symptom Study who tested positive for SARS-CoV-2 from May 26 to July 1, 2021 (Delta overwhelmingly predominant circulating UK variant), compared (1:1, age- and sex-matched) with individuals presenting from December 28, 2020 to May 6, 2021 (Alpha (B.1.1.7) predominant variant). We assessed illness (symptoms, duration, presentation to hospital) during Alpha- and Delta-predominant timeframes; and transmission, reinfection, and vaccine effectiveness during the Delta-predominant period.Findings3,581 individuals (aged 18 to 100 years) from each timeframe were assessed. The seven most frequent symptoms were common to both variants. Within the first 28 days of illness, some symptoms were more common with Delta vs. Alpha infection (including fever, sore throat and headache) and vice versa (dyspnoea). Symptom burden in the first week was higher with Delta vs. Alpha infection; however, the odds of any given symptom lasting ≥7 days was either lower or unchanged. Illness duration ≥28 days was lower with Delta vs. Alpha infection, though unchanged in unvaccinated individuals. Hospitalisation for COVID-19 was unchanged. The Delta variant appeared more (1·47) transmissible than Alpha. Re-infections were low in all UK regions. Vaccination markedly (69-84%) reduced risk of Delta infection.InterpretationCOVID-19 from Delta or Alpha infections is clinically similar. The Delta variant is more transmissible than Alpha; however, current vaccines show good efficacy against disease.FundingUK Government Department of Health and Social Care, Wellcome Trust, UK Engineering and Physical Sciences Research Council, UK Research and Innovation London Medical Imaging & Artificial Intelligence Centre for Value Based Healthcare, UK National Institute for Health Research, UK Medical Research Council, British Heart Foundation, Alzheimer’s Society, and ZOE Limited.Research in contextEvidence before this studyTo identify existing evidence for differences (including illness, transmissibility, and vaccine effectiveness) from SARS-CoV-2 infection due to Alpha (B.1.1.7) and Delta (B.1.617.2) variants, we searched PubMed for peer-reviewed articles and medRxiv for preprint publications between March 1 and November 18, 2021 using keywords (“SARS-CoV-2” OR “COVID-19”) AND (“delta variant” OR “B.1.617.2”) AND (symptom* OR transmiss* OR “disease duration” OR “illness duration” OR “symptom* duration”). Searches were not restricted by language. Among 169 identified PubMed articles, we found evidence that Delta variant has increased replication capacity (from 4-fold, up to 21-fold, compared with wild-type) and greater transmissibility (estimated between +20% and +97%), compared with previous strains. Currently available vaccines may have 2- to 5-fold lower neutralizing response to Delta vs. previous variants, depending on vaccine formulation, although their protective effect against severe disease and death appears to remain strong. REACT-1 study found that in UK infections were increasing exponentially in the 5-17-year old children in September 2021, coinciding with the start of the autumn school term in England. This was interpreted as an effect of the relatively low rate of vaccinated individuals in this age group. Other studies found that in unvaccinated individuals, Delta variant may be associated with higher odds of pneumonia, oxygen requirement, emergency care requests, ICU admission, and death. In a study of 27 (mainly young) cases, 22 persons were symptomatic, with fever (41%), cough (33%), headache (26%), and sore throat (26%) the commonest symptoms. We found no studies, beyond case series, investigating symptom and/or illness duration due to Delta variant infection otherwise.Added value of this studyUsing data from one of the largest UK citizen science epidemiological initiatives, we describe and compare illness (symptom duration, burden, profile, risk of long illness, and hospital attendance) in symptomatic community-based adults presenting when either the Alpha or Delta variant was the predominant circulating strain of SARS-CoV-2 in the UK. We assess evidence of transmission, reinfection, and vaccine effectiveness. Our data show that the seven most common symptoms with Delta infection were the same as with Alpha infection. Risks of illness duration ≥7 days and ≥28 days, and of requiring hospital care, were not increased. In line with previous research, we found increased transmissibility of Delta vs. previous variants; and no evidence of increased re-infection rates. Our data support high vaccine efficacy of BNT162b2 and ChAdOx1 nCoV-19 formulations against Delta variant infection. Overall, our study adds quantitative information regarding meaningful clinical differences in COVID-19 due to Delta vs. other variants.Implications of all the available evidenceOur observational data confirm that COVID-19 disease in UK in adults is generally comparable to infection with the Alpha variant, including in elderly individuals. Our data contribute to epidemiological surveillance from the wider UK population and may capture information from COVID-19 presentation within the community that might be missed in healthcare-based surveillance. Our data may be useful in informing healthcare service planning, vaccination policies, and measures for social protection.

BACKGROUND: COVID-19 vaccines show excellent efficacy in clinical trials and effectiveness in real-world data, but some people still become infected with SARS-CoV-2 after vaccination. This study aimed to identify risk factors for post-vaccination SARS-CoV-2 infection and describe the characteristics of post-vaccination illness.METHODS: This prospective, community-based, nested, case-control study used self-reported data (eg, on demographics, geographical location, health risk factors, and COVID-19 test results, symptoms, and vaccinations) from UK-based, adult (≥18 years) users of the COVID Symptom Study mobile phone app. For the risk factor analysis, cases had received a first or second dose of a COVID-19 vaccine between Dec 8, 2020, and July 4, 2021; had either a positive COVID-19 test at least 14 days after their first vaccination (but before their second; cases 1) or a positive test at least 7 days after their second vaccination (cases 2); and had no positive test before vaccination. Two control groups were selected (who also had not tested positive for SARS-CoV-2 before vaccination): users reporting a negative test at least 14 days after their first vaccination but before their second (controls 1) and users reporting a negative test at least 7 days after their second vaccination (controls 2). Controls 1 and controls 2 were matched (1:1) with cases 1 and cases 2, respectively, by the date of the post-vaccination test, health-care worker status, and sex. In the disease profile analysis, we sub-selected participants from cases 1 and cases 2 who had used the app for at least 14 consecutive days after testing positive for SARS-CoV-2 (cases 3 and cases 4, respectively). Controls 3 and controls 4 were unvaccinated participants reporting a positive SARS-CoV-2 test who had used the app for at least 14 consecutive days after the test, and were matched (1:1) with cases 3 and 4, respectively, by the date of the positive test, health-care worker status, sex, body-mass index (BMI), and age. We used univariate logistic regression models (adjusted for age, BMI, and sex) to analyse the associations between risk factors and post-vaccination infection, and the associations of individual symptoms, overall disease duration, and disease severity with vaccination status.FINDINGS: Between Dec 8, 2020, and July 4, 2021, 1 240 009 COVID Symptom Study app users reported a first vaccine dose, of whom 6030 (0·5%) subsequently tested positive for SARS-CoV-2 (cases 1), and 971 504 reported a second dose, of whom 2370 (0·2%) subsequently tested positive for SARS-CoV-2 (cases 2). In the risk factor analysis, frailty was associated with post-vaccination infection in older adults (≥60 years) after their first vaccine dose (odds ratio [OR] 1·93, 95% CI 1·50-2·48; pINTERPRETATION: To minimise SARS-CoV-2 infection, at-risk populations must be targeted in efforts to boost vaccine effectiveness and infection control measures. Our findings might support caution around relaxing physical distancing and other personal protective measures in the post-vaccination era, particularly around frail older adults and individuals living in more deprived areas, even if these individuals are vaccinated, and might have implications for strategies such as booster vaccinations.FUNDING: ZOE, the UK Government Department of Health and Social Care, the Wellcome Trust, the UK Engineering and Physical Sciences Research Council, UK Research and Innovation London Medical Imaging and Artificial Intelligence Centre for Value Based Healthcare, the UK National Institute for Health Research, the UK Medical Research Council, the British Heart Foundation, and the Alzheimer's Society.

BackgroundCOVID-19 vaccines show excellent efficacy in clinical trials and real-world data, but some people still contract SARS-CoV-2 despite vaccination. This study sought to identify risk factors associated with SARS-CoV-2 infection post-vaccination and describe characteristics of post-vaccination illness.MethodsAmongst 1,102,192 vaccinated UK adults from the COVID Symptom Study, 2394 (0.2%) cases of post-vaccination SARS-CoV-2 infection were identified between 8th December 2020 and 1st May 2021. Using a control group of vaccinated individuals testing negative, we assessed the associations of age, frailty, comorbidity, area-level deprivation and lifestyle factors with infection. Illness profile post-vaccination was assessed using a second control group of unvaccinated cases.FindingsOlder adults with frailty (OR=2.78, 95% CI=[1.98-3.89], p-valueInterpretationOur findings suggest that older individuals with frailty and those living in most deprived areas are at increased risk of infection post-vaccination. We also showed reduced symptom burden and duration in those infected post-vaccination. Efforts to boost vaccine effectiveness in at-risk populations, and to targeted infection control measures, may still be appropriate to minimise SARS-CoV-2 infection.FundingThis work is supported by UK Department of Health via the National Institute for Health Research (NIHR) comprehensive Biomedical Research Centre (BRC) award to Guy’s & St Thomas’ NHS Foundation Trust in partnership with King’s College London and King’s College Hospital NHS Foundation Trust and via a grant to ZOE Global; the Wellcome Engineering and Physical Sciences Research Council (EPSRC) Centre for Medical Engineering at King’s College London (WT 203148/Z/16/Z). Investigators also received support from the Chronic Disease Research Foundation, the Medical Research Council (MRC), British Heart Foundation, the UK Research and Innovation London Medical Imaging & Artificial Intelligence Centre for Value Based Healthcare, the Wellcome Flagship Programme (WT213038/Z/18/Z and Alzheimer’s Society (AS-JF-17-011), and the Massachusetts Consortium on Pathogen Readiness (MassCPR).Research in contextEvidence before this studyTo identify existing evidence for risk factors and characteristics of SARS-CoV-2 infection post-vaccination, we searched PubMed for peer-reviewed articles published between December 1, 2020 and May 18, 2021 using keywords (“COVID-19” OR “SARS-CoV-2”) AND (“Vaccine” OR “vaccination”) AND (“infection”) AND (“risk factor*” OR “characteristic*”). We did not restrict our search by language or type of publication. Of 202 articles identified, we found no original studies on individual risk and protective factors for COVID-19 infection following vaccination nor on nature and duration of symptoms in vaccinated, community-based individuals. Previous studies in unvaccinated populations have shown that social and occupational factors influence risk of SARS-CoV-2infection, and that personal factors (age, male sex, multiple morbidities and frailty) increased risk for adverse outcomes in COVID-19. Phase III clinical trials have demonstrated good efficacy of BNT162b2 and ChAdOx1 vaccines against SARS-CoV-2 infection, confirmed in published real-world data, which additionally showed reduced risk of adverse outcomes including hospitalisation and death.Added value of this studyThis is the first observational study investigating characteristics of and factors associated with SARS-CoV-2 infection after COVID-19 vaccination. We found that vaccinated individuals with frailty had higher rates of infection after vaccination than those without. Adverse determinants of health such as increased social deprivation, obesity, or a less healthy diet were associated with higher likelihood of infection after vaccination. In comparison with unvaccinated individuals, those with post-vaccination infection had fewer symptoms of COVID-19, and more were entirely asymptomatic. Fewer vaccinated individuals experienced five or more symptoms, required hospitalisation, and, in the older adult group, fewer had prolonged illness duration (symptoms lasting longer than 28 days).Implications of all the available evidenceSome individuals still contract COVID-19 after vaccination and our data suggest that frail older adults and those living in more deprived areas are at higher risk. However, in most individuals illness appears less severe, with reduced need for hospitalisation and lower risk of prolonged illness duration. Our results are relevant for health policy post-vaccination and highlight the need to prioritise those most at risk, whilst also emphasising the balance between the importance of personal protective measures versus adverse effects from ongoing social restrictions. Strategies such as timely prioritisation of booster vaccination and optimised infection control could be considered for at-risk groups. Research is also needed on how to enhance the immune response to vaccination in those at higher risk.

The internal energy distribution of ammonia formed in the dissociative recombination (DR) of NH4+ with electrons has been studied by an imaging technique at the ion storage ring CRYRING. The DR process resulted in the formation of NH3 + H (0.90 ± 0.01), with minor contributions from channels producing NH2 + H2 (0.05 ± 0.01) and NH2 + 2H (0.04 ± 0.02). The formed NH3 molecules were highly internally excited, with a mean rovibrational energy of 3.3 ± 0.4 eV, which corresponds to 70% of the energy released in the neutralization process. The internal energy distribution was semiquantitatively reproduced by ab initio direct dynamics simulations, and the calculations suggested that the NH3 molecules are highly vibrationally excited while rotational excitation is limited. The high internal excitation and the translational energy of NH3 and H will influence their subsequent reactivity, an aspect that should be taken into account when developing detailed models of the interstellar medium and ammonia-containing plasmas.

On account of its high efficiency, speed and unmatched selectivity, the Resonance Ionization Laser Ion Source (RILIS) is the preferred method for ionizing the nuclear reaction products at the ISOLDE on-line isotope separator facility. By exploiting the unique electronic energy level ‘fingerprint’ of a chosen element, the RILIS process of laser step-wise resonance ionization enables an ion beam of high chemical purity to be sent through the mass selective separator magnet. The isobaric purity of a beam of a chosen isotope is therefore greatly increased. The RILIS, comprising of up to three frequency tunable pulsed dye lasers has been upgraded with the installation of a Nd:YAG pump laser as a replacement for the old Copper Vapor Laser (CVL) system. A summary of the current Nd:YAG pumped RILIS performance is given. To accompany the RILIS pump laser upgrade, a new ionization scheme for manganese has been developed at the newly constructed LAser Resonance Ionization Spectroscopy (LARIS) laboratory and successfully applied for on-line RILIS operation. An overview of the LARIS facility is given along with details of the ionization scheme development work for manganese.

The resonance ionization laser ion source (RILIS) at the ISOLDE on-line isotope separator is based on the selective excitation of atomic transitions by tunable laser radiation. New ion beams have been produced with RILIS in recent years: Sb, Sc, Dy, Au, Hg and Po. In total, isotopes of 26 different elements have been selectively laser-ionized and separated at ISOLDE. In order to facilitate the work on development of atomic ionization schemes an off-line laser laboratory has been established at CERN. Operating independently of the on-line RILIS setup, this laboratory will be capable of providing extensive data on atomic transitions, in particular between highly excited and auto-ionizing atomic states, which are required for the improvement of the RILIS efficiency. Additionally, the program of upgrading the on-line RILIS system by the implementation of solid state lasers will be presented.

In this paper we report the results of a study on the dissociative recombination (DR) of the diacetylene cation, C4D2+, which has been carried out at the ion storage ring CRYRING in Stockholm, Sweden. The energy-dependent absolute DR cross-section as well as the branching fractions at ∼0 eV collision energy were measured. The DR cross-section was best fitted using the expression σ(E) = (7.5 ± 1.5) × 10−16 × E−(1.29±0.03) cm2 over the collision energy range 1–100 meV. The thermal rate coefficient was deduced from the cross-section to be α(T) = (1.10 ± 0.15) × 10−6 × (T/300)−(0.79±0.03) cm3/s. The reported branching fractions for C4D2+ agree with previous experiments on the DR of C4H2+ performed at the ASTRID storage ring in Aarhus, Denmark, and furthermore, indicate that the DR of C4D2+ possesses only two channels leading to the following products: C4D + D (75%) and C2D + C2D (25%).

The possibility of an extraterrestrial origin of biomolecule building blocks has been a subject of intense discussions for many years. The detection of amino acids in meteorites opens the possibility of a delivery of biomolecules synthesized in the interstellar medium or star-forming regions to the primeval Earth. Whereas it can be doubted if more complex species like amino acids can survive the strong UV radiation in the early Solar System, this does not necessary hold for more primitive precursor molecules like nitriles. These compounds can also be synthesized very efficiently in methane-nitrogen dominated atmospheres like the one present on Titan and the early ages of Earth. This Contribution focuses on the formation and degradation processes of nitriles in interstellar clouds and planetary atmospheres and on their possible role in the generation of biomolecules.

(2007). Experimental determination of dissociative recombination reaction pathways and absolute reaction cross-sections of CH2OH + , CD2OD + and CD2. Molecular Physics: Vol. 105, A Special Issue In Honour of John M. Brown, pp. 899-906.

The branching ratios of the different reaction pathways and the overall rate coefficients of the dissociative recombination reactions of CH3OH2+ and CD3OD2+ have been measured at the CRYRING storage ring located in Stockholm, Sweden. Analysis of the data yielded the result that formation of methanol or deuterated methanol accounted for only 3 and 6% of the total rate in CH3OH2+ and CD3OD2+, respectively. Dissociative recombination of both isotopomeres mainly involves fragmentation of the C-O bond, the major process being the three-body break-up forming CH3, OH and H (CD3, OD and D). The overall cross sections are best fitted by sigma = 1.2 +/- 0.1 x 10(-15) E(-1.15 +/- 0.02) cm2 and sigma = 9.6 +/- 0.9 x 10(-16) E(-1.20 +/- 0.02) cm2 for CH3OH2+ and CD3OD2+, respectively. From these values thermal reaction rate coefficients of k(T) = 8.9 +/- 0.9 x 10(-7) (T/300)(-0.59 +/- 0.02) cm3 s(-1) (CH3OH2+) and k(T) = 9.1 +/- 0.9 x 10(-7) (T/300)(-0.63 +/- 0.02) cm3 s(-1) (CD3OD2+) can be calculated. A non-negligible formation of interstellar methanol by the previously proposed mechanism via radiative association of CH3+ and H2O and subsequent dissociative recombination of the resulting CH3OH2+ ion to yield methanol and hydrogen atoms is therefore very unlikely.

The paper reports an investigation of the dissociative recombination of at the heavy-ion storage ring CRYRING. The absolute cross-section has been measured as a function of centre-of-mass energy ...

Branching ratios and absolute cross sections have been measured for the dissociative recombination of HCS+ and OCS+ at the CRYRING ion storage ring. In the case of OCS+, the channel leading to CO + S (83%) dominates, whereas the other exoergic pathways leading to CS + O (14%) and C + SO (3%) are of lesser importance. In the case of HCS+, fracture of the C–S bond is predominant (81%), with the production of H + CS accounting for the remainder (19%). The cross section of the reaction could be fitted by the expressions σ = 1.41 × 10-15E(eV)-1.11 and 4.47 × 10-16E(eV)-1.14 cm2 for HCS+ and OCS+, respectively. The derived energy dependences of the thermal reaction rate coefficients can be fitted by k(T) = 9.7 × 10-7(T/300)-0.57 and 3.5 × 10-7(T/300)-0.62 cm3 s-1 for HCS+ and OCS+, respectively. We use these data to perform model calculations on the HCS+/CS abundance ratio in dark clouds and find that the models using the UMIST and Ohio State University databases have even more difficulty in accounting for the large observed ratio.

The dissociative recombination and excitation of CF+ have been measured at the ASTRID and CRYRING storage rings. Though examination of the available potential energy curves would suggest that the recombination rate would be large for this ion, in fact a rate constant of 5.2 ± 1.0 × 10−8 (Te/300)−0.8 cm3 s−1 was found. The recombination cross section at low energies falls off to a minimum at 0.5 eV centre-of-mass collision energy but exhibits resonances at energies above this. The dissociative excitation cross section leading to C+ + F was also measured and this displays an onset beginning at about 7 eV.

This contribution describes the use of the RoentDek hexanode delay line detector to detect fragments from the dissociative recombination of O2+ in an experiment at the ion storage ring CRYRING, Manne Siegbahn Laboratory, Stockholm. In this experiment, the fragments have a maximum time- and position-separation of 20 ns and 40 mm, respectively. The position resolution obtained was 0.16 mm (FWHM) on the 67 mm diameter detector. The time resolution obtained from the time-of-arrival difference between the product fragments was about 1 ns. The detector system handles event rates as large as 30 kHz. Techniques for the calibration of the absolute position of particles on the detector are discussed.

We present dissociative recombination measurements, using the CRYRING ion storage ring, of H3+ ions produced in a supersonic expansion discharge source. Before and after the CRYRING measurements, the ion source was characterized in Berkeley using infrared cavity ringdown spectroscopy, and was found to exhibit a typical rotational temperature of ~30 K. Our measurement of the dissociative recombination cross section using this ion source revealed resonances that had not been observed clearly in previous experiments that used rotationally hot ion sources. Based on the present measurements, we infer a thermal dissociative recombination rate coefficient for ions at interstellar temperatures of ~ 2.6 × 10−7 cm3s−1. Our results are in general agreement with theoretical calculations of the dissociative recombination cross section by Kokoouline and Greene. We will review the enigma of the abundance of H3+ in the diffuse interstellar medium, and discuss the impact of these experiments, especially in the context of the recent observation of H3+ towards ζ Persei.

Cross sections and branching ratios for the dissociative recombination (DR) reactions of the astrophysically important ions HN2+, HCO+, DOCO+, and SO2+ at reactant kinetic energies from 1 to 1000 meV have been measured using the CRYRING ion storage ring facility at the Manne Siegbahn Laboratory, Stockholm University. Whereas the break-up of the N-N bond leading to NH + N is the major pathway in the DR of HN2+, the analogous reaction in HCO+ almost exclusively leads to H and CO. In the DR of both DOCO+ and SO2+ three-body break-up was observed. Inclusion of the newly measured branching ratios into a standard model on dark interstellar clouds leads to an improvement of the predictions of such models, especially concerning the abundances of nitrogen compounds. The impact of these newly found branching ratios and reaction rates on the chemistry of different astronomical environments like dark clouds, circumstellar envelopes and planetary ionospheres, is discussed.

The dissociative recombination of Na(+)(D(2)O) ion has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). The cross section has been measured as a function of center-of-mass energy ranging from 1 meV to 0.1 eV and found to have an E(-1.37) dependence. The rate coefficient has been deduced to be (2.3+/-0.32)x10(-7)(T(e)/300)(-0.95+/-0.01) cm(3) s(-1) for T(e)=50-1000 K. The branching ratios have been measured at 0 eV. Of the four energetically accessible dissociation channels, three channels are found to occur although the channel that breaks the weak Na(+)-D(2)O bond is by far dominant.

Branching ratios and absolute cross sections have been measured for the dissociative recombination of DCCCN+ and DCCCND+ using the CRYRING ion storage ring. In the case of DCCCN+ the dissociation y ...

Branching ratios and absolute cross sections have been measured for the dissociative recombination of C3H4+ using the CRYRING ion storage ring. The pre-eminent channel involves the production of C3 ...

Branching ratios and absolute cross sections have been measured for the dissociative recombination of (SO2+)-O-18 using the CRYRING ion storage ring. The branching ratio of the (SO2+)-O-18 + e(-)-->(SO)-O-18+O-18 channel amounts to 61%, while the three-body breakup (SO2+)-O-18 + e(-)-->S+2(18)O accounts for the remaining 39% of the total reaction. The cross section of the reaction could be fitted by the expression sigma=(1.2+/-0.4)x10(-15) E-0.96+/-0.02 cm(2), which leads to a thermal reaction rate of k(T)=(4.6+/-0.2)x10(-7)(T/300 K)(-0.52+/-0.02) cm(3) mol(-1) s(-1).

Branching ratios and absolute cross sections have been measured for the dissociative recombination of N2H+ using the CRYRING ion storage ring. It has been found that the channel N2H+ + e- → N2 + H accounts for only 36% of the total reaction and that the branching into the other exoergic pathway, N2H+ + e- → NH + N, consequently amounts to 64%. The cross section of the reaction could be fitted by the expression σ = (2.4 ± 0.4) × 10-16E-1.04±0.02 cm2, which leads to a thermal reaction rate of k(T) = (1.0 ± 0.2) × 10-7(T/300)-0.51±0.02 cm3 s-1, in favorable agreement with previous flowing afterglow Langmuir probe measurements at room temperature, although our temperature dependence is very different. The implications of these measurements for the chemistry of interstellar clouds are discussed. A standard model calculation for a dark cloud predicts a slight increase of N2H+ in the dark clouds but a five- to sevenfold increase of the NH concentration as steady state is reached.

This paper reports an experimental investigation of the electron impact detachment of C−4. We observe structure in the electron impact cross section for detaching a single electron from a C−4 cluster anion, which we attribute to the formation and decay of the C2−4 dianion. The system is energetically unstable and very rapidly decays via double autodetachment. The energy and width of the resonance were determined to be 8.8(5) eV and 1.4(5) eV, respectively, and the resonance lies 1.5(5) eV above the ground state of the neutral system. The experiment was conducted by merging monoenergetic electron and ion beams in the heavy ion storage ring CRYRING. The detachment channel was monitored by detecting neutral C4 fragments.

Branching ratios and absolute cross sections have been measured for the dissociative recombination of N2OD+ using the CRYRING ion storage ring. The most dominating pathways were found to be those leading to N2+OD (46%) and the three-body break-up producing N2+O+D (40%). The production of N2O is not observed. The cross section of the reaction could be fitted to the expression σ=1.25±0.25×10−15(E/eV)−1.24±0.02, which leads to a thermal reaction rate of k(T)=1.4±0.1×10−6(T/300)−0.74±0.02 cm3 s−1. The findings are compared with those of the related dissociative recombination of DOCO+ as well as with earlier flowing afterglow measurements.

Dissociative recombination (DR) of the water cluster ion D+(D2O)2 has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). Cluster ions were injected into the ring and accelerated to an energy of 2.28 MeV. The stored ion beam was merged with an almost monoenergetic electron beam, and neutral fragments produced by DR were detected by an energy-sensitive surface barrier detector. The first experimental determinations of the absolute DR cross section and branching ratios for a cluster ion are reported. The cross section for the process D+(D2O)2+e− is large and reaches 6⋅10−12 cm2 at a low center-of-mass collision energy of 0.001 eV. The cross section has an E−1.19±0.02 dependence in the energy range 0.001–0.0052 eV, and a steeper slope with an E−1.70±0.12 dependence for E=0.052–0.324 eV. The general trends are similar to the results for previously studied molecular ions, but the cross section is higher in absolute numbers for the cluster ion. Thermal rate coef...

Electron Impact Single Detachment (EISD) of F- has been studied using the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm, Sweden. F- ions stored in the ring were merged with an electron beam in one of the ring sections. Neutral F atoms produced in the EISD process were detected in the zero-degree direction using a surface barrier detector. The threshold for the detachment process was found to be around 7.6 eV, thus more than twice the binding energy of F-. The cross-sections increased smoothly up to 55 eV where it reached a maximum of 1.9×10 -16 cm 2 . At higher energies a slow decrease of the cross-section was observed, which follows the energy dependence predicted by the Bethe-Born approximation. The experiment showed that CRYRING can be used favourably for studies of anions, and several experiments are forthcoming.

We present the results of an experiment in which electrons have been scattered on CN- ions, over a collision energy range 0–60 eV. The experiment was performed at the heavy ion storage ring CRYRING. The CN- ions were stored in the ring and merged with a monoenergetic electron beam that was guided in to and out of the ring using strong magnetic fields. Both neutral and positive fragments from the collision process were detected with surface barrier detectors. It was found that pure detachment completely dominates over those channels which involves breaking the molecular bond. The threshold energy for the detachment process was found to be 7 eV. The cross section rose from zero to a maximum of about 5 · 10-16 cm2 just below 30 eV, after which it remained essentially constant. The threshold region was carefully investigated in an attempt to find resonance structure arising from the possible existence of the doubly charged ion, CN2-. The statistical uncertainty in the data was, however, too large to conclusively prove or disprove the existence of such a resonance.

The electron cooler at CRYRING is now operating with a superconducting gun solenoid and an electron beam that is adiabatically expanded with a factor of up to 100. This paper describes the new gun solenoid and electron gun. It presents measurements made on longitudinal cooling forces with different expansion factors, electron densities, magnetic field strengths and beam alignments. It also presents studies of a transverse beam instability that appears when a misalignment is introduced between ion and electron beams. Finally, some measurements of dielectronic recombination that directly yield transverse and longitudinal electron temperatures are discussed.

The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization on the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high-temperature, low-work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE / CERN, Geneva and RISIKO / University of Mainz.

The dissociative recombination of the ozone cation has been studied at the heavy-ion storage ring CRYRING. The total cross section and branching fractions have been measured. The cross section from {approx}0eV to 0.2 eV follows a nearly E{sup -1} dependence, which was theoretically predicted to be a characteristic of the direct dissociative recombination mechanism. The thermal rate coefficient has been deduced from the cross section to be 7.37x10{sup -7}(T/300){sup -0.55}cm{sup 3}s{sup -1}. The branching fraction analysis carried out at {approx}0eV interaction energy has shown a strong propensity (94%) to dissociate through the three-body channel. Due to the overwhelming dominance of this channel it has been investigated in more detail. Of the six energetically available three-body pathways only three are significantly populated, such that the production of O(S1) is highly unfavored and all atomic oxygen fragments are predominantly formed in P3 and D1 states. Analysis of the breakup geometries has been performed by means of the Dalitz plot. It is observed that the molecules dissociating through the O(P3)+O(P3)+O(P3) and O(P3)+O(P3)+O(D1) channels have an open linear geometry where the cleavage of two valence bonds occurs preferentially in unison, while the O(P3)+O(D1)+O(D1) breakup might proceed partly through a sequential mechanism.

We report an investigation into the dissociative recombination of the azide radical cation, N(3) (+). The reaction rate constant has been measured to be 6.47 x 10(-7) cm(3) s(-1) at room temperature. This value is smaller than those reported earlier for the ion-electron neutralization of N(3) (+) at nitrogen atmospheric pressure. A strong propensity to dissociate through the N(2)+N channel has been observed.

We report the first observation of almost exclusive three-body breakup in the dissociative recombination of a covalent triatomic molecular ion O3+. The three-body channel, constituting about 94% of the total reactivity, has been investigated in detail. The atomic fragments are formed in only the first two electronic states, 3P and 1D, while formation in the 1S state has not been observed. The breakup predominantly proceeds through dissociative states with linear geometry.

We present a technique for measuring the radiative lifetimes of metastable states of negative ions that involves the use of a heavy-ion storage ring. The method has been applied to investigate the radiative decay of the $n{p}^{3}\phantom{\rule{0.2em}{0ex}}^{2}P_{1∕2}$ levels of ${\mathrm{Te}}^{\ensuremath{-}}(n=5)$ and ${\mathrm{Se}}^{\ensuremath{-}}(n=4)$ and the $3{p}^{3}\phantom{\rule{0.2em}{0ex}}^{2}D$ state of ${\mathrm{Si}}^{\ensuremath{-}}$ for which the $J=3∕2$ and $5∕2$ levels were unresolved. All of these states are metastable and decay primarily by emission of $E2$ and $M1$ radiation. Multi Configuration Dirac-Hartree-Fock calculations of rates for the transitions in ${\mathrm{Te}}^{\ensuremath{-}}$ and ${\mathrm{Se}}^{\ensuremath{-}}$ yielded lifetimes of $0.45\phantom{\rule{0.3em}{0ex}}\mathrm{s}$ and $4.7\phantom{\rule{0.3em}{0ex}}\mathrm{s}$, respectively. The measured values agree well with these predicted values. In the case of the $^{2}D$ state of ${\mathrm{Si}}^{\ensuremath{-}}$, however, our measurement was only able to set a lower limit on the lifetime. The upper limit of the lifetime that can be measured with our apparatus is set by how long the ions can be stored in the ring, a limit determined by the rate of collisional detachment. Our lower limit of $1\phantom{\rule{0.3em}{0ex}}\mathrm{min}$ for the lifetime of the $^{2}D$ state is consistent with both the calculated lifetimes of $162\phantom{\rule{0.3em}{0ex}}\mathrm{s}$ for the $^{2}D_{3∕2}$ level and $27.3\phantom{\rule{0.3em}{0ex}}\mathrm{h}$ for the $^{2}D_{5∕2}$ level reported by O'Malley and Beck and $14.5\phantom{\rule{0.3em}{0ex}}\mathrm{h}$ and $12.5\phantom{\rule{0.3em}{0ex}}\mathrm{h}$, respectively, from our Breit-Pauli calculations.

International audience; Cross sections and branching ratios are presented for the dissociative recombination of the CF+2 and CF+3 ions with electrons. It is found that the channel producing CF + F is dominant for the reaction with CF+2 and the production of CF2 + F is dominant for the reaction with CF+3. The cross sections for these two ions are very similar.

A merged beam technique has been used to investigate the fragmentation of the Cl-2(-) ion in collisions with electrons over an energy range of 0-200 eV. We have measured absolute cross sections for ...

Product branching ratios and thermal rate coefficients for the dissociative recombination of C3D(+)7 and C4D(+)9 have been measured in the ion storage ring CRYRING. The results for C3D(+)7 are believed to be slightly more accurate than those obtained earlier for C3H(+)7. Only the C-C bond breaking channels could be measured for C4D(+)9 and were found to be in excellent agreement with earlier data.

This paper presents the first dissociative recombination (DR) measurement of electrons with rotationally and vibrationally cold $\mathrm{H}_{3}^{+}$ ions. A dc discharge pinhole supersonic jet source was developed and characterized using infrared cavity ringdown spectroscopy before installation on the CRYRING ion storage ring for the DR measurements. Rotational state distributions $({T}_{\mathrm{rot}}\ensuremath{\sim}30\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ produced using the source were comparable to those in the diffuse interstellar medium. Our measurement of the electron energy dependence of the DR cross section showed resonances not clearly seen in experiments using rotationally hot ions, and allowed calculation of the thermal DR rate coefficient for ions at interstellar temperatures, ${\ensuremath{\alpha}}_{\mathrm{DR}}(23\phantom{\rule{0.3em}{0ex}}\mathrm{K})=2.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$. This value is in general agreement with recent theoretical predictions by Kokoouline and Greene [Phys. Rev. A 68, 012703 (2003)]. The branching fractions of the two breakup channels, $\mathrm{H}+\mathrm{H}+\mathrm{H}$ and $\mathrm{H}+{\mathrm{H}}_{2}$, have also been measured for rotationally and vibrationally cold $\mathrm{H}_{3}^{+}$.

Branching ratios of the dissociative recombination reactions of the astrophysically relevant ions DCO+, N2H+ and DOCO+ (as substitute for HOCO+) have been measured using the CRYRING storage ring at the Manne Siegbahn Laboratory at the University of Stockholm, Sweden. For DCO+, the channel leading to D and CO was by far the most important one (branching ratio 0.88), only small contributions of the CD + O and OD + C product pathways (branching ratios 0.06 each) were recorded. In the case of N2H+ the surprising result of a break-up of the N-N bond to N and NH (branching ratio 0.64) was found with the branching ratio of the N2 + H product channel therefore displaying a branching ratio of only 0.36. In the case of DOCO+, the three-body break-up into D + O + CO dominated (branching ratio 0.68), whereas the contribution of the CO2 + H channel was only minute (0.05). The remaining share (branching ratio 0.27) was taken by the pathway leading to OH + CO. For the dissociative recombination of N2H+ and DOCO+ also absolute reaction cross sections were obtained in the collisional energy range between 0 and 1 eV. From these cross sections it was possible to work out the thermal rate constants, which were found to be k(T) = 1.0+/-0.1 x 10(-7) (T/300 K)(-0.51+/-0.02) cm3 s(-1) and k(T) = 1.2+/-0.1 x 10(-6) (T/300 K)(-0.64+/-0.02) cm3 S(-1) for N2H+ and DOCO+, respectively.

The dissociative recombination (DR) process of NH4+ and ND4+ molecular ions with free electrons has been studied at the heavy-ion storage ring CRYRING (Manne Siegbahn Laboratory, Stockholm University). The absolute cross sections for DR of NH4+ and ND4+ in the collision energy range 0.001-1 eV are reported, and thermal rate coefficients for the temperature interval from 10 to 2000 K are calculated from the experimental data. The absolute cross section for NH4+ agrees well with earlier work and is about a factor of 2 larger than the cross section for ND4+. The dissociative recombination of NH4+ is dominated by the product channels NH3+H (0.85+/-0.04) and NH2+2H (0.13+/-0.01), while the DR of ND4+ mainly results in ND3+D (0.94+/-0.03). Ab initio direct dynamics simulations, based on the assumption that the dissociation dynamics is governed by the neutral ground-state potential energy surface, suggest that the primary product formed in the DR process is NH3+H. The ejection of the H atom is direct and leaves the NH3 molecule highly vibrationally excited. A fraction of the excited ammonia molecules may subsequently undergo secondary fragmentation forming NH2+H. It is concluded that the model results are consistent with gross features of the experimental results, including the sensitivity of the branching ratio for the three-body channel NH2+2H to isotopic exchange.