Search

Using the technique of stimulated emission pumping (SEP) spectroscopy, highly excited vibration–rotation states of the CH3O (X 2E) molecule were probed up to energies of E≤10 000 cm-1. The highest excitation energies exceed the asymptotic H–H2CO dissociation limit of the molecule [ΔrH00(H–H2CO)≊6900 cm-1]. Work was carried out at different experimental resolutions. First, low resolution survey SEP spectra were found to exhibit persistent vibrational structure up to energies far above the dissociation limit. The observed main features were found to be assignable, in a zero-order picture that leaves aside possible mode-to-mode couplings, to the progression of the excited C–O stretch vibration states (ν3). The widths of the respective features correspond to localized short-time vibrational motion for times of ≥0.3 ps (≥10 C–O vibrational periods). Second, in high resolution scans over the coarse vibrational features, characteristic clumps of individual vibration–rotation eigenstates were revealed. These clumps are ascribed to distinctive Franck–Condon active bright zero-order levels which are mixed with the large number of Franck–Condon inactive dark bath states. Under carefully selected conditions, the clumps could be attributed to states with defined and well known values of the total angular momentum quantum number J, which remains as a good quantum number in different coupling cases. These clump spectra will be analyzed quantitatively in the following paper with respect to their bearing for the intramolecular vibrational dynamics of highly excited CH3O (X) as a function of vibrational and rotational excitation. From the observed spectra, quantitative data can be obtained on the rate and extent of collision-free intramolecular vibrational and rovibrational energy redistribution (IVR and IRVR) processes, which would result after coherent ultrashort pulse excitation of... [ABSTRACT FROM AUTHOR]

The stimulated emission pumping (SEP) spectra of highly excited CH3O (X 2E) reported in the preceding paper [A. Geers, J. Kappert, F. Temps, and J. Wiebrecht, J. Chem. Phys. 101, 3618 (1994); paper I] are analyzed to extract quantitative data on the collision-free intramolecular vibrational dynamics of the molecules. Attention is focused on the spectra and dynamics of the excited C–O stretch vibration (ν3) states at energies between 3 000 cm-1≤E≤10 000 cm-1. The spectra are found to exhibit a rather sudden transition at E≊5000 cm-1 from the regular, assignable properties at low energies to the ‘‘statistical’’ region at high energies. This IVR ‘‘threshold’’ is approximately 2000 cm-1 below the asymptotic H–H2CO dissociation limit of the molecule. The observed densities of states at these energies approach the full J- and symmetry-sorted rovibronic densities estimated from harmonic state counts. The nearest-neighbor level spacing distribution in the spectra and the magnitude of the inferred root mean square level coupling matrix elements support the assumption of nearly ‘‘ergodic’’ molecular properties in this region. From computed time autocorrelation functions, the IVR lifetimes of the highly excited C–O stretch states are found to be of the order of τ≊0.2–0.3 ps (v3=5 to 6). Evidence is obtained from some spectra for two-tier IVR processes with characteristic time scales of 0.2 and 2 ps, respectively. The highest excited C–O stretch states at energies above ≊8000 cm-1 (v3≥8) appear to be coupled only weakly to neighboring background states. This last observation hints at the existence of quasistable periodic orbits, which are embedded in the quasicontinuum of dissociative states at these energies. [ABSTRACT FROM AUTHOR]

Vibration rotation quantum state resolved unimolecular dissociation lifetimes of highly excited CH3O (X 2E) molecules have been measured using the method of stimulated emission pumping (SEP) in connection with transient laser induced fluorescence (TLIF) excitation spectroscopy for preparing selected single target states and for their time resolved detection. The measured decay rate constants for six closely spaced levels with precisely known total excitation energies around E(X)≊7450 cm-1 and J=0.5 (or 1.5) were found to vary erratically between 9·105 s-1≤k≤3·107 s-1. The results are compared to predictions by unimolecular rate theory and discussed with respect to the question of mode specific vs statistical reactivity. [ABSTRACT FROM AUTHOR]

Experiments have been carried out using hot band laser induced fluorescence (LIF) excitation and stimulated emission pumping (SEP) spectroscopy to characterize the excited doubly degenerate ν6 vibrational mode of CH3O (X 2E) which is of interest with respect to the Jahn–Teller effect in the molecule. Rotationally resolved spectra were recorded for the A 2A1X 2E, 610 and 310610 bands. The observed line structures indicate that these bands must be assigned to Δj=3/2 parallel (ΔK=0) vibronic bands. No evidence could yet be obtained for the corresponding Δj=1/2 vibronic transitions assumed previously. The results imply that the linear Jahn–Teller effect for ν6 is very small. Instead, coupling between the A 2A1 and the X 2E states by a pseudo-Jahn–Teller interaction operator is suggested as a plausible mechanism for the observation of the forbidden transitions. [ABSTRACT FROM AUTHOR]

Ptychopteracastor Keresztes & Kappert, sp. nov. and P.pollux Keresztes & Török, sp. nov. both belong to the subgenus Ptychoptera (Paraptychoptera)Tonnoir (1919) and are described from boggy headwaters in the south Balkan area. These new species are closely related to the range-restricted P.helena Peus, 1958, which is known only from Oiti village, Mount Oeta, Phthioitis region, Greece and, together with P.lacustris , forms a morphologically well-defined unit in the subgenus Paraptychoptera. Based on cladistic analyses of 53 different morphological characters using the male antenna, wing, and genital structures, a general revision of the "lacustris" group is proposed with a dichotomous key of Paraptychoptera species., (Lujza Keresztes, Jürgen Kappert, Mária Henning, Edina Török.)

Background: Treatment with clozapine can affect the heart, leading to serious complications such as myocarditis and cardiomyopathy. When in their early stages both illnesses are difficult to diagnose; this can have serious consequences. Recent analyses of clozapine data suggest that particularly myocarditis is possibly more common than has been assumed hitherto., Aim: To determine the frequency of these complications and to find out what diagnostic tests are available and whether it is necessary or possible to adjust current guidelines on these complications., Method: The relevant literature was consulted via PubMed, Embase Psychiatry and Psycinfo on the basis of the keywords 'clozapine' and 'myocarditis', 'cardiomyopathy' and 'heart failure'., Results: Studies showed that the incidence of myocarditis varied from 0.015 to 1.3%. Cardiomyopathy was the subject of fewer studies, one study reported an incidence of 0.022%. More than 50% of the cases of myocarditis developed during the first few weeks of treatment, the average time being about 15 days. For an early diagnosis it is important to monitor the patient's symptoms carefully, especially during the first four weeks following the start of medication. Monitoring should include laboratory tests and electrocardiography. Echocardiography and MRI can be useful additions to the diagnostic process., Conclusions: Early diagnosis of myocarditis is important because it is a serious condition. Timely recognition of subclinical myocarditis could possibly prevent later complications such as cardiomyopathy. Clinical guidelines are proposed on the basis of the literature.

The incidence of cholelithiasis and rate of cholecystectomy has been studied in three differently selected groups: first, in 3842 autopsies during the years 1969-1977, second, in 6564 patients who underwent to x-ray examination during 1970-1974 for various reasons; third in 163 patients aged over 50 years referred for reasons other than abdominal discomfort. The incidence of dyspeptic symptoms was registered in the patients of the last group. The rate of cholelithiasis and cholecystectomy in the first group corresponds well to that in the second group. In men and women over 60 years, who had been referred to the outpatients clinic for reasons not related to abdominal pain, the rate of cholelithiasis was 33% and 42% respectively. This finding corresponds to that of the first and second group. There was no difference in the incidence of dyspeptic symptoms among the patients of the last group with and without cholelithiasis. The results suggests that in the old patients the incidence of silent gallstones increases, but that the rate of cholecystectomy did not.