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Granular matter like sand is composed of a large number of interacting grains and is, thus, expected to be amenable to a statistical physics treatment. Yet, the frictional properties of grains make the statistical physics of granular matter significantly different from the equilibrium statistical physics of atomic or molecular systems. We use three simple models to illustrate some of the key concepts of the statistical physics introduced by Edwards and co-workers more than 30 years ago to describe shaken granular piles: non-interacting frictional grains attached to a wall by a spring, a chain of frictional grains connected by springs, and a simplified mean-field model of a granular packing. We observe that a chain of frictional grains connected by springs exhibits a critical point at an infinite effective temperature (i.e., infinitely strong shaking) at odds with the zero-temperature critical point generically found in one-dimensional systems at thermal equilibrium in the presence of local interactions. Since the late 20th century, granular materials have been recognized as forming a distinct state of matter, neither solid nor liquid, but amenable to a statistical description. It turns out that dissipation, through inter-grain friction, governs the large-scale properties of these systems, so that the usual Boltzmann–Gibbs statistics is replaced by the Edwards statistics. These statistics are full of surprises. For instance, model granular systems can exhibit a critical point at infinite-temperature. To know more, you can delve into this paper, which can be used in advanced statistical physics courses, or as a graduate-level introduction to soft matter. [ABSTRACT FROM AUTHOR]

Within the framework of three-dimensional non-relativistic noncommutative quantum phase-space (3D-NRNCPS) symmetries, we study the three-dimensional deformed Schrödinger equation (3D-DSE) using the improved modified Kratzer plus generalized inverse quadratic Yukawa potential (IMK-GIQYP) and the improved modified screened Kratzer plus inversely quadratic Yukawa potential (IMSK-IQYP) models. For this consideration, the well-known generalized Bopp's shifts method and standard perturbation theory are used to solve the DSE in the 3D-NRNCPS regime. For the homogeneous (H2, N2 and I2) and heterogeneous (CO, CH and NO) diatomic molecules, the new non-relativistic energy equation and eigenfunction for the IMK-GIQYP and the IMSK-IQYP models in the presence of deformation phase-space are obtained to be sensitive to the atomic quantum numbers (j , l , s and m), the mixed potential depths ( D e , r e and V) and ( D e , r e , q and V 1 ), the screening parameters (δ and φ), and non-commutativity parameters (Θ / Φ ¯ , χ / χ ¯ and ζ / ζ ¯) for the IMK-GIQYP and the IMSK-IQYP, respectively. We investigate the newly obtained bound state eigenvalues of the DSE in 3D-NRNCPS symmetries using the IMK-GIQYP and the IMSK-IQYP, with appropriate adjustments made to the improved modified Kratzer potential, improved modified screened Kratzer potential, improved generalized inverse quadratic Yukawa potential model and improved inversely quadratic Yukawa potential model. Additionally, in 3D-NRNCPS symmetries, the thermal properties of the IMK-GIQYP and the IMSK-IQYP, including their partition function, mean energy, free energy, specific heat and entropy, are thoroughly examined. Significant areas, including atomic and molecular physics, find many uses for this study. [ABSTRACT FROM AUTHOR]

The manuscript discusses the concepts of spin–orbit and spin–spin coupling in atomic physics and Molecular Quantum Similarity (MQS) in molecular clusters. spin–orbit and spin–spin coupling arises from the interaction between an electron's spin and its motion around the nucleus and electron–electron interaction and plays a crucial role in determining energy levels and spectral lines in atoms with heavy nuclei. On the other hand, MQS is a computational approach to compare the electronic density distributions in different molecular systems. In this order of ideas, the study aims to answer questions about electronic and structural differences caused by the spin–orbit and spin–spin coupling from the initial geometry [Steradians (SR) geometry] using the MQS framework. The MQS is based on the Molecular Quantum Similarity Measure (MQSM) using different positive operators such as Dirac delta and Coulomb operators to quantify the similarity between molecular systems. The paper presents tables with MQSM indices and Euclidean distances for different molecular clusters using initial geometry vs. geometry involved spin–orbit and spin–spin coupling. The scalar, spin–orbit and spin–spin relativistic coupling were incorporated using Amsterdam Density Functional code. The results show significant coupling of spin–orbit and spin–spin coupling on the similarity measures between different molecules. The manuscript suggests that understanding the relationship between spin–orbit and spin–spin coupling and quantum similarity could lead to deeper insights into electronic interactions in complex molecular systems and has potential applications in quantum mechanics and molecular physics. [ABSTRACT FROM AUTHOR]

Kasha's rule generally holds true for solid-state molecular systems, where the rates of internal conversion and vibrational relaxation are sufficiently higher than the luminescence rate. In contrast, in systems where plasmons and matter interact strongly, the luminescence rate is significantly enhanced, leading to the emergence of luminescence that does not obey Kasha's rule. In this work, we investigate the anti-Kasha emissions of single molecules, free-base and magnesium naphthalocyanine (H2Nc and MgNc), in a plasmonic nanocavity formed between the tip of a scanning tunneling microscope (STM) and metal substrate. A narrow-line tunable laser was employed to precisely reveal the excited-state levels of a single molecule located under the tip and to selectively excite it into a specific excited state, followed by obtaining a STM-photoluminescence (STM-PL) spectrum to reveal the energy relaxation from the state. The excitation to higher-lying states of H2Nc caused various changes in the emission spectrum, such as broadening and the appearance of new peaks, implying the breakdown of Kasha's rule. These observations indicate emissions from the vibrationally excited states in the first singlet excited state (S1) and second singlet excited state (S2), as well as internal conversion from S2 to S1. Moreover, we obtained direct evidence of electronic and vibronic transitions from the vibrationally excited states, from the STM-PL measurements of MgNc. The results obtained herein shed light on the energy dynamics of molecular systems under a plasmonic field and highlight the possibility of obtaining various energy-converting functions using anti-Kasha processes. [ABSTRACT FROM AUTHOR]

Dieter Gerlich, a renowned scientist in the field of molecular physics, passed away unexpectedly in 2020. He was known for his experimental work on collisions related to astro and ion chemistry. Throughout his career, Gerlich developed innovative tools and methods for guiding and trapping ions and charged particles, which are widely used in research and analytical instrumentation. His research focused on understanding collision processes, such as proton collisions with hydrogen molecules, and he made significant contributions to our understanding of these fundamental processes. Gerlich's work also extended to studying collisions between ions and molecules at thermal energies, simulating conditions found in interstellar molecular clouds. He was a generous collaborator and mentor, and his contributions to the field of molecular physics are highly regarded. [Extracted from the article]

The stability analysis of possibly time varying positive semigroups on non-necessarily compact state spaces, including Neumann and Dirichlet boundary conditions is a notoriously difficult subject. These crucial questions arise in a variety of areas of applied mathematics, including nonlinear filtering, rare event analysis, branching processes, physics and molecular chemistry. This article presents an overview of some recent Lyapunov-based approaches, focusing principally on practical and powerful tools for designing Lyapunov functions. These techniques include semigroup comparisons as well as conjugacy principles on non-necessarily bounded manifolds with locally Lipschitz boundaries. All the Lyapunov methodologies discussed in the article are illustrated in a variety of situations, ranging from conventional Markov semigroups on general state spaces to more sophisticated conditional stochastic processes possibly restricted to some non-necessarily bounded domains, including locally Lipschitz and smooth hypersurface boundaries, Langevin diffusions as well as coupled harmonic oscillators. [ABSTRACT FROM AUTHOR]

We give a simple introduction to the properties and use of ultrastable optical cavities, which are increasingly common in atomic and molecular physics laboratories for stabilizing the frequency of lasers to linewidths at the kHz level or below. Although the physics of Fabry–Perot interferometers is part of standard optics curricula, the specificities of ultrastable optical cavities, such as their high finesse, fixed length, and the need to operate under vacuum, can make their use appear relatively challenging to newcomers. Our aim in this work is to bridge the gap between generic knowledge about Fabry–Perot resonators and the specialized literature about ultrastable cavities. The intended audience includes students setting up an ultrastable cavity in a research laboratory for the first time and instructors designing advanced laboratory courses on optics and laser stabilization techniques. [ABSTRACT FROM AUTHOR]

The article focuses on the Nobel Prize in Chemistry 2023 awarded to Aleksey Yekimov, Louis E. Brus, and Moungi G. Bawendi for their discovery and synthesis of quantum dots. Topics include the history of quantum size effects, the pioneering experiments in the 1970s, the independent work of Yekimov and Brus in the 1980s, and the subsequent breakthroughs by Bawendi in the 1990s, leading to the widespread applications of quantum dots in scientific research and commercial products.

The well-established and rapidly expanding field of molecular processes in excited systems, facilitated by the use of light sources, garners significant research interest from numerous experimental and theoretical groups worldwide. This highly interdisciplinary field establishes extensive connections with atomic, molecular and optical physics, astrophysics, biophysics, physical chemistry, solid-state physics and even molecular biology. The present topic provides an advanced overview of research activities in cutting-edge areas such as ultrafast lasers, nanoscale systems, atomic and molecule collisions on surfaces and molecular photofragmentation processes. The contributions to this subject encompass experimental, theoretical and computational studies conducted both at the fundamental level, exploring elementary mechanisms, and at a more applied level, addressing the requirements of diverse applications in nanotechnology and materials science. [ABSTRACT FROM AUTHOR]

We report on the design and characterization of a compact microwave antenna for atomic and molecular physics experiments. The antenna is comprised of four loop antennas arranged in a cloverleaf shape, allowing for precise adjustment of polarization by tuning the relative phase of the loops. We optimize the antenna for left-circularly polarized microwaves at 3.5 GHz and characterize its near-field performance using ultracold NaCs molecules as a precise quantum sensor. Observing an unusually high Rabi frequency of 2π × 46.1(2) MHz, we extract an electric field amplitude of 33(2) V/cm at 22 mm distance from the antenna. The polarization ellipticity is 2.3(4)°, corresponding to a 24 dB suppression of right-circular polarization. The cloverleaf antenna is planar and provides large optical access, making it highly suitable for quantum control of atoms and molecules and potentially other quantum systems that operate in the microwave regime. [ABSTRACT FROM AUTHOR]

The prediction of molecular properties is a crucial task in the field of drug discovery. Computational methods that can accurately predict molecular properties can significantly accelerate the drug discovery process and reduce the cost of drug discovery. In recent years, iterative updates in computing hardware and the rise of deep learning have created a new and effective path for molecular property prediction. Deep learning methods can leverage the vast amount of data accumulated over the years in drug discovery and do not require complex feature engineering. In this review, we summarize molecular representations and commonly used datasets in molecular property prediction models and present advanced deep learning methods for molecular property prediction, including state‐of‐the‐art deep learning networks such as graph neural networks and Transformer‐based models, as well as state‐of‐the‐art deep learning strategies such as 3D pre‐train, contrastive learning, multi‐task learning, transfer learning, and meta‐learning. We also point out some critical issues such as lack of datasets, low information utilization, and lack of specificity for diseases. [ABSTRACT FROM AUTHOR]

By using generalized fractional derivative, the parametric generalized fractional Nikiforov-Uvarov (NU) method is introduced. The second-order parametric generalized differential equation is exactly solved in the fractional form. The obtained results are applied on the extended Cornell potential, the pesudoharmonic potential, the Mie potential, the Kratzer-Fues potential, the harmonic oscillator potential, the Morse potential, the Woods-Saxon potential, the Hulthen potential, the deformed Rosen-Morse potential and the P schl-Teller potential which play an important role in the fields of molecular and atomic physics. The special of classical cases are obtained from the fractional cases at which are agreement with recent works.

Predicting the structural properties of water and simple fluids confined in nanometer scale pores and channels is essential in, for example, energy storage and biomolecular systems. Classical continuum theories fail to accurately capture the interfacial structure of fluids. In this work, we develop a deep learning-based quasi-continuum theory (DL-QT) to predict the concentration and potential profiles of a Lennard-Jones (LJ) fluid and water confined in a nanochannel. The deep learning model is built based on a convolutional encoder–decoder network (CED) and is applied for high-dimensional surrogate modeling to relate the fluid properties to the fluid–fluid potential. The CED model is then combined with the interatomic potential-based continuum theory to determine the concentration profiles of a confined LJ fluid and confined water. We show that the DL-QT model exhibits robust predictive performance for a confined LJ fluid under various thermodynamic states and for water confined in a nanochannel of different widths. The DL-QT model seamlessly connects molecular physics at the nanoscale with continuum theory by using a deep learning model. [ABSTRACT FROM AUTHOR]

Under vibrational strong coupling (VSC), the formation of molecular polaritons may significantly modify the photo-induced or thermal properties of molecules. In an effort to understand these intriguing modifications, both experimental and theoretical studies have focused on the ultrafast dynamics of vibrational polaritons. Here, following our recent work [Li et al., J. Chem. Phys. 154, 094124 (2021)], we systematically study the mechanism of polariton relaxation for liquid CO2 under a weak external pumping. Classical cavity molecular dynamics (CavMD) simulations confirm that polariton relaxation results from the combined effects of (i) cavity loss through the photonic component and (ii) dephasing of the bright-mode component to vibrational dark modes as mediated by intermolecular interactions. The latter polaritonic dephasing rate is proportional to the product of the weight of the bright mode in the polariton wave function and the spectral overlap between the polariton and dark modes. Both these factors are sensitive to parameters such as the Rabi splitting and cavity mode detuning. Compared to a Fermi's golden rule calculation based on a tight-binding harmonic model, CavMD yields a similar parameter dependence for the upper polariton relaxation lifetime but sometimes a modest disagreement for the lower polariton. We suggest that this disagreement results from polariton-enhanced molecular nonlinear absorption due to molecular anharmonicity, which is not included in our analytical model. We also summarize recent progress on probing nonreactive VSC dynamics with CavMD. [ABSTRACT FROM AUTHOR]

The research works of Professor Michael Brunger have spanned a period of more than 40 years. In this paper, we set out to record his contributions in the field of Atomic and Molecular Physics by using a bibliometric analysis approach. Firstly, we give an overview of his publication and citations, and we highlight his top 10 cited papers and their impact in this field of research. Secondly, we explore the diversity of his research areas in general. Finally, we perform an analysis of his research collaborations with international groups with clear visualization. We have used a wide range of bibliometric indicators: citation indicators; indices of structural difference; indicators of scientific collaboration. [ABSTRACT FROM AUTHOR]

Structural imaging of transient excited-state species is a key goal of molecular physics, promising to unveil rich information about the dynamics underpinning photochemical transformations. However, separating the electronic and nuclear contributions to the spectroscopic observables is challenging, and typically requires the application of high-level theory. Here, we employ site-selective ionisation via ultrashort soft X-ray pulses and time-resolved Coulomb explosion imaging to interrogate structural dynamics of the ultraviolet photochemistry of carbon disulfide. This prototypical system exhibits the complex motifs of polyatomic photochemistry, including strong non-adiabatic couplings, vibrational mode couplings, and intersystem crossing. Immediately following photoexcitation, we observe Coulomb explosion signatures of highly bent and stretched excited-state geometries involved in the photodissociation. Aided by a model to interpret such changes, we build a comprehensive picture of the photoinduced nuclear dynamics that follows initial bending and stretching motions, as the reaction proceeds towards photodissociation. Coulomb Explosion imaging is a promising technique to study the ultrafast nuclear dynamics which underpin molecular photochemistry. By initiating Coulomb explosion through soft X-ray ionization, the authors are able to image ultrafast nuclear dynamics of a prototypical photoreaction. [ABSTRACT FROM AUTHOR]

The Institute of Modern Physics (IMP) at Fudan University in China is a renowned research institution specializing in nuclear physics. Established in 1958, the institute offers degrees at the bachelor's, master's, and doctoral levels in various nuclear science and technology fields. IMP has a distinguished faculty, including internationally recognized scholars, and actively participates in international cooperation projects. Their research spans nuclear physics, particle physics, atomic and molecular physics, nuclear technology, and nuclear-related theory and computational physics. They employ large scientific devices both domestically and internationally for their research. The text highlights IMP's research and development efforts, including advancements in high time resolution electronic readout, silicon photomultipliers, and scintillators. They are also engaged in experiments related to neutrinoless double beta decay and collaborate with international partners. IMP's research in atomic and molecular physics focuses on highly charged ions and their applications in plasma physics and precision measurement. They also prioritize nuclear technology and its applications, utilizing ion beam technologies for microbeam analysis, biomedical physics, and archaeology. Additionally, IMP conducts research in nuclear-related theory and computational physics, with a focus on atomic structure, reactor design, and high-energy density physics. [Extracted from the article]

Many experiments in atomic and molecular physics require simultaneous frequency stabilization of multiple lasers. We present a stabilization scheme based on a scanning transfer cavity lock that is simple, stable, and easily scalable to many lasers at minimal cost. The scheme is based on the Red Pitaya STEMlab platform, with custom software developed and implemented to achieve up to 100 Hz bandwidth. As an example demonstration, we realize simultaneous stabilization of up to four lasers and a reduction of long-term drifts to well below 1 MHz/h. This meets typical requirements, e.g., for experiments on laser cooling of molecules. [ABSTRACT FROM AUTHOR]

[366] P.A.B. Haase, D.J. Doeglas, A. Boeschoten, E. Eliav, M. Ilias, P. Aggarwal, H.L. Bethlem, A. Borschevsky, K. Esajas, Y. Hao, S. Hoekstra, V.R. Marshall, Th. Meijknecht, M. Mooij, K. Steinebach, R.G.E. Timmermans, A. Touwen, W. Ubachs, L. Willmann, Y. Yin B Systematic study and uncertainty evaluation of P,T-odd relativistic enhancement factors in BaF b J. Chem. Phys. [25] W. Ubachs, K.S.E. Eikema, W. Hogervorst, B Narrowband extreme ultraviolet radiation tunable in the range 90.5-95 nm: application to spectroscopy of N SB 2 sb b Appl. Phys. [346] O. Versolato, A. Bayerle, M. Bayraktar, L. Behnke, H. Bekker, Z. Bouza, J. Colgan, J.R. Crespo Lopez-Urrutia, M.J. Deuzeman, R. Hoekstra, D. Kurilovich, B. Liu, R. Meijer, A. Neukirch, L. Poirier, S. Rai, A. Ryabtsev, J. Scheers, R. Schupp, J. Sheil, F. Torretti, W. Ubachs, S. Witte, B Spectroscopic investigations of YAG-laser-driven microdroplet-tin plasma sources of extreme ultraviolet radiation for nanolithography b J. Phys. [302] M.J. Deuzeman, A.S. Stodolna, E.E.B. Leerssen, A. Antoncecchi, N. Spook, T. Kleijntjens, J. Versluis, S. Witte, K.S.E. Eikema, W. Ubachs, R. Hoekstra, O.O. Versolato, B Ion distribution and ablation depth measurements of a fs-ps laser-irradiated solid tin target b J. Appl. Phys. [281] M.L. Niu, E.J. Salumbides, W. Ubachs, B Test of quantum chemistry in vibrationally-hot hydrogen molecules b J. Chem. Phys. [Extracted from the article]

Aconitine (AC), which is the primary bioactive diterpene alkaloid derived from Aconitum L plants, have attracted considerable interest due to its unique structural feature. Additionally, AC demonstrates a range of biological activities, such as its ability to enhance cardiac function, inhibit tumor growth, reduce inflammation, and provide analgesic effects. However, the structure-activity relationships of AC are remain unclear. A clear understanding of these relationships is indeed critical in developing effective biomedical applications with AC. In line with these challenges, this paper summarized the structural characteristics of AC and relevant functional and bioactive properties and the structure-activity relationships presented in biomedical applications. The primary temporal scope of this review was established as the period spanning from 2010 to 2023. Subsequently, the objective of this review was to provide a comprehensive understanding of the specific action mechanism of AC, while also exploring potential novel applications of AC derivatives in the biomedical field, drawing upon their structural characteristics. In conclusion, this review has provided a comprehensive analysis of the challenges and prospects associated with AC in the elucidation of structure-bioactivity relationships. Furthermore, the importance of exploring modern biotechnology approaches to enhance the potential biomedical applications of AC has been emphasized. [ABSTRACT FROM AUTHOR]

The contemporary paper refers back to the instability of linear in GeX2 (X=F, Cl & Br) molecules because of the vibronic coupling effect. Optimization and the following frequency calculations in those molecules found out that every one of those molecules were unstable in high symmetry linear (with D∞h symmetry) geometry and their systems have been bent to lower C2v symmetry geometry. On this work, we've used, TD-DFT (B3LYP/6-31G (d) calculations to gain the strength curves of the ground and excited in the bending directions Q (πu) of compounds 1-3. The vibronic coupling interaction between 1∑g+ ground and the first 1∑u excited states in the Q (∑u) direction via (1∑g+ + 1πu) ⊗ πu PJTE problem was the reason for the symmetry breaking phenomenon. Additionally, changing atoms with different elements together with the electronegative exchange and the degree of overlap at once have an effect on the pattern of molecular orbitals. The NBO calculations were carried out to define a stability measure through the stabilization energy, E2 parameter. According to the consequences received from the vibronic principle of PJT, the bent shape of those analogs is the result of LP(3) X → LP*(2)Ge1 electron delocalization .The PJT stabilization strength decreases from compound 1 to compound three. Moreover, by the decrease of the energy gaps between reference states (Δ) the primary force constant of the ground state in the Q (πu) direction (K0) could decrease from compound 1 to compound 3. [ABSTRACT FROM AUTHOR]

Controlling the coherence between light and matter has enabled the radiation of electromagnetic waves with a spectral purity and stability that defines the Système International (SI) second. Transitions between hyperfine levels in atoms are accessible in the microwave and optical domains, but faithfully transferring such stability to other frequency ranges of interest requires additional components such as optical frequency combs. Such spectral purity and stability are specifically sought out for the terahertz domain for both scientific and commercial applications, including precision studies of molecular physics, next-generation wireless communications, quantum sensors, and terahertz frequency standards. Currently, there is a lack of native frequency references in this spectral range, which is essential for the consistency of measurements and traceability. Small-scale terahertz oscillators, which leverage dissipative Kerr soliton microcombs, present a promising avenue for the generation of terahertz waves that rival the spectral purity of electronic alternatives. Here, we experimentally demonstrate the rotational spectroscopy of nitrous oxide (N2O) with a microcomb-based oscillator. To mitigate the frequency drift encompassed in such waves, we lock the frequency of the microcomb terahertz oscillator to that of a rotational transition of N2O, reducing the fractional frequency stability to a level of 5 × 10−12 at 10 s of averaging time. These results constitute a high performance terahertz oscillator that can be scaled down to a compact size while circumventing the need for frequency multiplication or division of frequency standards. This demonstrates a foundational component needed for future terahertz applications. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) processing in the interstellar medium (ISM) induces the dehydrogenation of hydrocarbons. Aliphatics, including alkanes, are present in different interstellar environments, being prevalently formed in evolved stars; thus, the dehydrogenation by UV photoprocessing of alkanes plays an important role in the chemistry of the ISM, leading to the formation of unsaturated hydrocarbons and eventually to aromatics, the latter ubiquitously detected in the ISM. Here, through combined experimental results and ab initio calculations, we show that UV absorption (mainly at the Ly α emission line of hydrogen at 121.6 nm) promotes an alkane to an excited Rydberg state from where it evolves toward fragmentation, inducing the formation of olefinic C=C bonds, which are necessary precursors of aromatic hydrocarbons. We show that the photochemistry of aliphatics in the ISM does not primarily produce direct hydrogen elimination but preferential C–C photocleavage. Our results provide an efficient synthetic route for the formation of unsaturated aliphatics, including propene and dienes, and suggest that aromatics could be formed in dark clouds by a bottom-up mechanism involving molecular fragments produced by UV photoprocessing of aliphatics.

Seven rotational and fine-structure transitions of the deuterated molecular ion SD ^+ in the X ^3 Σ ^− ground electronic state have been measured in the 271–863 GHz region in the laboratory. This ion has been produced by direct-current glow discharge using a mixture of D _2 S and argon in a free space cell in a temperature range of −140°C to −160°C. The rotational, centrifugal distortion, spin–spin interaction, and hyperfine constants have been determined; the standard deviation of the residuals in the fitting is 109 kHz. The set of obtained spectroscopic parameters provides a list of accurate submillimeter rest frequencies of SD ^+ for astronomical detection. We have investigated lines of SD ^+ toward the quasar PKS 1830-211 using the Atacama Large Millimeter/submillimeter Array archive, as the z = 0.89 molecular absorber exists in front of this quasar. A data set covering the 297 GHz region includes the N _J = 2 _3 –1 _2 transition at 561 GHz due to redshift, providing an upper limit of the column density N _tot = 3 × 10 ^12 cm ^−2 for SD ^+ .

We report a combined experimental and theoretical study on the influence of microwave pulse durations on enantiomer-specific state transfer. Two triads of rotational states within a chiral molecule (1-indanol) are selected to address the possible scenarios. In the triad connected to the absolute ground state, the simplest triad that exists for all chiral molecules, the enantiomer-specific state transfer process simplifies into a sequence of two-level transitions. The second triad, including higher rotational states, represents a more generic scenario that involves multiple Rabi frequencies for each transition. Our study reveals that the conventional $\frac{\pi}{2}-\pi-\frac{\pi}{2}$ pulse sequence is not the optimal choice, except for the ideal case when in the simplest triad only the lowest state is initially populated. We find that employing a shorter duration for the first and last pulse of the sequence leads to significantly higher state-specific enantiomeric enrichment, albeit at the expense of overall population in the target state. Our experimental results are in very good agreement with theory, substantiating the quantitative understanding of enantiomer-specific state transfer.

The phase stability and equilibria of carbon dioxide are investigated from 125–325 K and 1–10 000 atm using extensive molecular dynamics (MD) simulations and the Two-Phase Thermodynamics (2PT) method. We devise a direct approach for calculating phase diagrams, in general, by considering the separate chemical potentials of the isolated phase at specific points on the P–T diagram. The unique ability of 2PT to accurately and efficiently approximate the entropy and Gibbs energy of liquids allows for assignment of phase boundaries from relatively short (∼100 ps) MD simulations. We validate our approach by calculating the critical properties of the flexible elementary physical model 2, showing good agreement with previous results. We show, however, that the incorrect description of the short-range Pauli force and the lack of molecular charge polarization lead to deviations from experiments at high pressures. We, thus, develop a many-body, fluctuating charge model for CO2, termed CO2–Fq, from high level quantum mechanics (QM) calculations that accurately capture the condensed phase vibrational properties of the solid (including the Fermi resonance at 1378 cm−1) as well as the diffusional properties of the liquid, leading to overall excellent agreement with experiments over the entire phase diagram. This work provides an efficient computational approach for determining phase diagrams of arbitrary systems and underscores the critical role of QM charge reorganization physics in molecular phase stability. [ABSTRACT FROM AUTHOR]

Understanding current-induced bond rupture in single-molecule junctions is both of fundamental interest and a prerequisite for the design of molecular junctions, which are stable at higher-bias voltages. In this work, we use a fully quantum mechanical method based on the hierarchical quantum master equation approach to analyze the dissociation mechanisms in molecular junctions. Considering a wide range of transport regimes, from off-resonant to resonant, non-adiabatic to adiabatic transport, and weak to strong vibronic coupling, our systematic study identifies three dissociation mechanisms. In the weak and intermediate vibronic coupling regime, the dominant dissociation mechanism is stepwise vibrational ladder climbing. For strong vibronic coupling, dissociation is induced via multi-quantum vibrational excitations triggered either by a single electronic transition at high bias voltages or by multiple electronic transitions at low biases. Furthermore, the influence of vibrational relaxation on the dissociation dynamics is analyzed and strategies for improving the stability of molecular junctions are discussed. [ABSTRACT FROM AUTHOR]

The development and implementation of modern experimental methods in interdisciplinary projects promote the solution of fundamental problems in molecular biology and medicine. One of these problems is the understanding of the physics of molecular interactions in a narrow (<1 nm) surface layer of cellular lipid membranes (hydration layer of the membrane), where most of the important electrochemical interactions with ions and proteins, transmembrane transport of molecules, and endocytosis occur. The solution of this problem requires noninvasive methods sensitive to changes in the molecular structure of the surface layer of membranes. The aims of this work are to describe advantages of nonlinear optical microscopy and spectroscopy for the study of structural and electrostatic features of lipid membranes, to present the developed method for the visualization of the hydration of lipid membranes, and to discuss the limits of applicability of this method. [ABSTRACT FROM AUTHOR]

Enabling elliptically polarized high-order harmonics overcomes a historical limitation in the generation of this highly nonlinear process in atomic, molecular and optical physics with applications in other branches. Here, we shed new light on a controversy between experimental observations and theoretical predictions on the possibility to generate harmonics with large ellipticity using two bichromatic laser pulses which are linearly polarized in orthogonal directions. Results of numerical calculations confirm the previous experimental data that in short laser pulses even harmonics with large ellipticity can be obtained for the interaction of such cross-polarized laser pulses with atoms initially in a s- or p-state, while odd harmonics have low ellipticity. The amount of the ellipticity can be controlled via the relative carrier-envelope phase of the pulses, their intensity ratio and the duration of the pulses. [ABSTRACT FROM AUTHOR]

Employing Fourier‐transform technique, this work derives the molecular multicenter integrals for the modified Slater‐type orbitals (STOs) with arbitrary principal and angular quantum numbers, in which the spherical harmonics parts are the homogeneous solutions of original STOs. The integrands include spherical Bessel functions and associated Legendre functions. One‐electron three‐center nuclear attraction integral and two‐electron four‐center Coulomb repulsion integral are presented as numerical integrations in two dimensions and three dimensions, respectively. A simple Python script is provided to run the formulas. The correctness and computational efficiency of the script have been verified. [ABSTRACT FROM AUTHOR]

Efforts over 40 yr still leave the source of astronomical infrared emission bands largely unidentified. Here, we report the first laboratory infrared (6–25 μ m) spectra of gas-phase fullerene-metal complexes, [C60-Metal]+ (Metal = Fe, V) and show with density functional theory calculations that complexes of C60 with cosmically abundant metals, including Li, Na, K, Mg, Ca, Al, V, and Fe, all have similar spectral patterns. Comparison with observational infrared spectra from several fullerene-rich planetary nebulae demonstrates a strong positive linear cross-correlation. The infrared features of [C60-Metal]+ coincide with four bands attributed earlier to neutral C60 bands and in addition also with several bands unexplained to date. Abundance and collision theory estimates indicate that [C60-Metal]+ could plausibly form and survive in astrophysical environments. Hence, [C60-Metal]+ are proposed as promising carriers, in supplement to C60, of observational bands, potentially representing the largest molecular species in space other than C60, C60+, and C70. [ABSTRACT FROM AUTHOR]

The faint CO gases in debris disks are easily dissolved into C by UV irradiation, while CO can be reformed via reactions with hydrogen. The abundance ratio of C/CO could thus be a probe of the amount of hydrogen in the debris disks. We conduct radiative transfer calculations with chemical reactions for debris disks. For a typical dust-to-gas mass ratio of debris disks, CO formation proceeds without the involvement of H2 because a small amount of dust grains makes H2 formation inefficient. We find that the CO to C number density ratio depends on a combination of n H Z 0.4 χ −1.1, where n H is the hydrogen nucleus number density, Z is the metallicity, and χ is the far-UV flux normalized by the Habing flux. Using an analytic formula for the CO number density, we give constraints on the amount of hydrogen and metallicity for debris disks. CO formation is accelerated by excited H2 when either the dust-to-gas mass ratio is increased or the energy barrier of chemisorption of hydrogen on the dust surface is decreased. This acceleration of CO formation occurs only when the shielding effects of CO are insignificant. In shielded regions, the CO fractions are almost independent of the parameters of dust grains. [ABSTRACT FROM AUTHOR]

We propose an effective general approach for accurately calculating the electron-electron, nuclear-electron and nuclear-nuclear Coulomb electrostatic interaction energies. Since these interaction energies are fundamental terms in the ab initio, density function and semi-empirical theories, their general examination will make an important contribution to the accurate calculation of the physical and chemical properties of atoms and molecules. It is well known that electron-electron, nuclear-electron and nuclear-nuclear Coulomb electrostatic interaction energies can be reduced to basic two-center Coulomb integrals. The analytical calculation of electrostatic interaction energies with respect to basic two-center Coulomb integrals over Slater type orbitals (STOs) in molecular coordinate systems allows for the routine evaluation of molecular structures and their related properties. In this study, we introduce a new full analytical algorithm for calculating the basic two-center Coulomb integrals over STOs using Guseinov's auxiliary functions, especially the interactions between electrons. The auxiliary functions are calculated by using the exact recurrence relations developed by Guseinov. Our new approach is successfully tested on data from previously published studies, and can be recommended for the evaluation of related problems in atomic and molecular physics. [ABSTRACT FROM AUTHOR]

We present a robust approach to generate a continuously tunable, low phase noise, Hz linewidth and mHz/s stability THz emission in the 0.1 THz to 1.4 THz range. This is achieved by photomixing two commercial telecom, distributed feedback lasers locked by optical-feedback onto a single highly stable V-shaped optical cavity. The phase noise is evaluated up to 1.2 THz, demonstrating Hz-level linewidth. To illustrate the spectral performances and agility of the source, low pressure absorption lines of methanol and water vapors have been recorded up to 1.4 THz. In addition, the hyperfine structure of a water line at 556.9 GHz, obtained by saturation spectroscopy, is also reported, resolving spectral features displaying a full-width at half-maximum of 10 kHz. The present results unambiguously establish the performances of this source for ultra-high resolution molecular physics. The authors demonstrate a very stable yet broadly tunable photonic THz source, characterized from 2 GHz to 1.4 THz. A very narrow Lamb dip feature is observed in a water absorption line, showcasing its potential for sub-kHz resolution spectroscopy. [ABSTRACT FROM AUTHOR]

Structural imaging of transient excited-state species is a key goal of molecular physics, promising to unveil rich information about the dynamics underpinning photochemical transformations. However, separating the electronic and nuclear contributions to the spectroscopic observables is challenging, and typically requires the application of high-level theory. Here, we employ site-selective ionisation via ultrashort soft X-ray pulses and time-resolved Coulomb explosion imaging to interrogate structural dynamics of the ultraviolet photochemistry of carbon disulfide. This prototypical system exhibits the complex motifs of polyatomic photochemistry, including strong non-adiabatic couplings, vibrational mode couplings, and intersystem crossing. Immediately following photoexcitation, we observe Coulomb explosion signatures of highly bent and stretched excited-state geometries involved in the photodissociation. Aided by a model to interpret such changes, we build a comprehensive picture of the photoinduced nuclear dynamics that follows initial bending and stretching motions, as the reaction proceeds towards photodissociation. Coulomb Explosion imaging is a promising technique to study the ultrafast nuclear dynamics which underpin molecular photochemistry. By initiating Coulomb explosion through soft X-ray ionization, the authors are able to image ultrafast nuclear dynamics of a prototypical photoreaction. [ABSTRACT FROM AUTHOR]

In The Logic of Life , François Jacob reconstructed the history of heredity from the seventeenth century to the present, emphasizing the role of physics in the development of biology. Quantum mechanics provided questions, methods, and techniques to molecular biologists. In the 1960s, physics also provided the organizational model. Jacob worked on the creation of the European Molecular Biology Laboratory, on the model of CERN (European Organization for Nuclear Research). I argue that reflection on the relation between molecular biology and physics played a part in the making of The Logic of Life. Between the mid-1960s and the early 1970s, Jacob focused on relations between the "genealogy" of his molecular biology work and the development of physics at scientific, institutional, and historical levels. He thus brought molecular biology to the attention of a larger public, following the history of the Institut Pasteur, whose public mission had to be reaffirmed to grant its survival. With The Logic of Life , Jacob became an influential intellectual who engaged with scholars in human sciences. He promoted his view of the development of molecular biology as a model for a possible new discipline: bioanthropology. [ABSTRACT FROM AUTHOR]

Highly accurate theoretical predictions of transition energies in the radium monofluoride molecule, 226RaF, and radium cation, 226Ra+, are reported. The considered transition X2Σ1/2 → A2Π1/2 in RaF is one of the main features of this molecule and can be used to laser-cool RaF for a subsequent measurement of the electron electric dipole moment. For molecular and atomic predictions, we go beyond the Dirac–Coulomb Hamiltonian and treat high-order electron correlation effects within the coupled cluster theory with the inclusion of quadruple and ever higher amplitudes. The effects of quantum electrodynamics (QED) are included non-perturbatively using the model QED operator that is now implemented for molecules. It is shown that the inclusion of the QED effects in molecular and atomic calculations is a key ingredient in resolving the discrepancy between the theoretical values obtained within the Dirac–Coulomb–Breit Hamiltonian and the experiment. The remaining deviation from the experimental values is within a few meV. This is more than an order of magnitude better than the "chemical accuracy," 1 kcal/mol = 43 meV, that is usually considered as a guiding thread in theoretical molecular physics. [ABSTRACT FROM AUTHOR]

The elegant expression of Förster that predicts the well-known 1/R6 distance (R) dependence of the rate of energy transfer, although widely used, was derived using several approximations. Notable among them is the neglect of the vibrational relaxation in the reactant (donor) and product (acceptor) manifolds. Vibrational relaxation can play an important role when the energy transfer rate is faster than the vibrational relaxation rate. Under such conditions, donor to acceptor energy transfer can occur from the excited vibrational states. This phenomenon is not captured by the usual formulation based on the overlap of donor emission and acceptor absorption spectra. Here, we develop a Green's function-based generalized formalism and obtain an exact solution for the excited state population relaxation and the rate of energy transfer in the presence of vibrational relaxation. We find that the application of the well-known Förster's expression might lead to overestimation of R. [ABSTRACT FROM AUTHOR]

The goal of the molecular theory of gases is to understand the macroscopic properties of gases through an analysis of the behavior of its constituents, atoms, or molecules. If a molecule collides with the piston, it changes only its velocity component I v i SB I ix i sb perpendicular to the surface of the piston (i.e., in the I x i -direction), where the subscript I i i refers to the I i i th molecule of the considered gas. Work and the change in internal energy It is intuitively clear that when a molecule strikes a piston that moves toward the molecule, the speed of the molecule will be increased after the collision. [Extracted from the article]

Progress toward quantum technologies continues to provide essential new insights into the microscopic dynamics of systems in phase space. This highlights coherence effects whether these are due to ultrafast lasers whose energy width spans several states all the way to the output of quantum computing. Surprisal analysis has provided seminal insights into the probability distributions of quantum systems from elementary particle and also nuclear physics through molecular reaction dynamics to system biology. It is therefore necessary to extend surprisal analysis to the full quantum regime where it characterizes not only the probabilities of states but also their coherence. In principle, this can be done by the maximal entropy formalism, but in the full quantum regime, its application is far from trivial [S. Dagan and Y. Dothan, Phys. Rev. D 26, 248 (1982)] because an exponential function of non-commuting operators is not easily accommodated. Starting from an exact dynamical approach, we develop a description of the dynamics where the quantum mechanical surprisal, a linear combination of operators, plays a central role. We provide an explicit route to the Lagrange multipliers of the system and identify those operators that act as the dominant constraints. [ABSTRACT FROM AUTHOR]

We use new HCN(1–0) data from the ACA Large-sample Mapping Of Nearby galaxies in Dense gas (ALMOND) survey to trace the kpc-scale molecular gas density structure and CO(2–1) data from the Physics at High Angular resolution in Nearby GalaxieS–Atacama Large Millimeter/submillimeter Array (PHANGS–ALMA) to trace the bulk molecular gas across 25 nearby star-forming galaxies. At 2.1 kpc scale, we measure the density-sensitive HCN/CO line ratio and the star formation rate (SFR)/HCN ratio to trace the star formation efficiency in the denser molecular medium. At 150 pc scale, we measure structural and dynamical properties of the molecular gas via CO(2–1) line emission, which is linked to the lower resolution data using an intensity-weighted averaging method. We find positive correlations (negative) of HCN/CO (SFR/HCN) with the surface density, the velocity dispersion, and the internal turbulent pressure of the molecular gas. These observed correlations agree with expected trends from turbulent models of star formation, which consider a single free-fall time gravitational collapse. Our results show that the kpc-scale HCN/CO line ratio is a powerful tool to trace the 150 pc scale average density distribution of the molecular clouds. Lastly, we find systematic variations of the SFR/HCN ratio with cloud-scale molecular gas properties, which are incompatible with a universal star formation efficiency. Overall, these findings show that mean molecular gas density, molecular cloud properties, and star formation are closely linked in a coherent way, and observations of density-sensitive molecular gas tracers are a useful tool to analyse these variations, linking molecular gas physics to stellar output across galaxy discs. [ABSTRACT FROM AUTHOR]

In this paper, we perform a nonrelativistic study of Frost-Musulin potential (FMP) impacted by the external magnetic and AB flux fields for the CO and NO diatomic molecules using the Nikiforov-Uvarov method with the Greene-Aldrich approximation to the centrifugal barrier. The numerical computation of the proposed potential reveals that the combined impact of the magnetic and AB flux fields completely removes the degeneracy of the energy spectra and controls the behavior of the magnetocaloric effect (MCE) by acting as a regulating factor to cool or heat the MCE. Also, the thermomagnetic plots obtained for the analyzed dimer molecules agreed perfectly with previous work. This research has the potential to be applied in molecular physics and MCE studies for a variety of molecules. [ABSTRACT FROM AUTHOR]

Coacervates are complexes formed from a polymer-polymer or polymer-surfactant interaction. Coacervates formed by a cationic polymer and an anionic surfactant enabled the development of the first conditioning shampoos (also called 2-in-1 shampoos). The objective of this work is to contribute with the identification of formulation parameters that increase the formation of coacervates. Polymer charge, micelles charges and the total content of surfactants are determining factors in the formation of coacervates. Factors such as polymer molecular weight and ionic strength also contribute, although in lesser order of importance, to the formation of coacervates. However, the role played by the degree of hydrophilicity/hydrophobicity of the polymer, as well as the effect of different co-surfactants, has not been determined with certainty. In the present study, three different types of polymers and six types of co-surfactants will be evaluated, keeping constant the amount of anionic surfactant, total content of surfactants and ionic strength. These results will serve to optimize the formulation of conditioning hair cleaning products. [ABSTRACT FROM AUTHOR]

There is a market need for more sustainable laundry detergents. Consumers are looking for cleaning products that are biobased and biodegradable, but do not comprise on stain removal performance. Enzymes play a key role in today's liquid laundry detergents. This article reports on recent advances in biotechnology to improve the stability and low temperature performance of enzymes for laundry. It also demonstrates how protein engineering can enable detergent formulators to remove chemical stabilizers. [ABSTRACT FROM AUTHOR]

Creams, shower gels and bubble baths are often developed with a color concept to achieve a refreshing or relaxing effect or to emphasize certain ingredients. Natural extracts are particularly popular in natural cosmetics, but also come with challenges when used in aqueous products and their storage. With this study we propose a method to verify stability and to reconcile product efficacy and shelf life. We also highlight the advantages to not only work with coloring the product, but also pay attention to the design of the packages, especially with regards to colors and smart labelling, to support the appearance and message of the product. [ABSTRACT FROM AUTHOR]