Rotational Levels Research Articles

Vibrational ladder climbing dissociation of LiH molecules excited by non-chirped pulses

Vibrational ladder climbing (VLC) is one of the advanced methods for achieving molecular dissociation, usually requires the use of chirped laser pulses to adapt to the change of energy difference between molecular vibrational levels. In this work, a scheme is proposed for using non-chirped pulses to couple the vibrational rotational levels of excited state to realize VLC dissociation of LiH molecules in the excited state. The first pulse induces population excitation to the excited state A1Σ+, while the second pulse is used to drive the excited state vibrational levels population up step by step until dissociation occurs. The non-chirped pulse VLC dissociation dynamics is investigated using the time-dependent quantum wave packet theory method. The “”climb steps” process for excited state molecules at low full width at half maximum (FWHM) of the second laser pulse is demonstrated. The frequency has an obvious influence on the distribution of excited state vibrational rotational levels and further affects the relaxation process of the undissociated part and the angular distribution of dissociation products. It is also explained that the anomalous decrease of dissociation probability is caused by vibrational levels oscillation.

Measurements of the Rovibrationally Dependent Lifetimes of C2 in the 13Σg+ and f3Σg- States through the VUV-Pump-UV-Probe Scheme.

The dicarbon molecule, C2, is one of the most important diatomic species in various gaseous environments. Despite extensive spectroscopic studies in the last two centuries, the radiative and photodissociative properties of C2 in its highly excited electronic states are still largely unexplored, particularly in the short vacuum ultraviolet (VUV) region. In this study, the lifetimes of C2 for rotational levels in the recently identified 13Σg+ state up to the vibrational level ν' = 4 and in the f3Σg- state up to ν' = 2 are measured for the first time with a VUV-pump-UV-probe photoionization scheme. It is found that all rovibrational levels in the f3Σg- state have lifetimes shorter than the dynamical limit of ∼4.7 ns of the present method, and the lifetimes in the 13Σg+ state show obvious and complex dependence on the rotational and vibrational quantum levels. Generally, the lifetime in the 13Σg+ state becomes shorter at higher rotational and vibrational levels, i.e., the longest lifetime measured in the ν' = 0 level is ∼18 ns, while all rotational levels in the ν' = 4 level are found to have shorter lifetimes than ∼4.7 ns. This implies that predissociation might occur and become more prominent at the higher energy levels in the 13Σg+ state. The prominent dependence of the lifetime on the rotational, vibrational and electronic level indicates complex dynamical processes in the highly excited states of C2.

An Upgraded Line List for Radiative Transitions between the B 2Σ+, A 2Π, and X 2Σ+ States of the CN Radical

The global mass-invariant coupled-channel deperturbation model of the B 2Σ+, A 2Π, and X 2Σ+ states of the CN radical, which reproduces the overall rovibronic term values of mutually perturbed levels with almost spectroscopic accuracy, has been utilized to produce complete line lists of radiative transitions between the X 2Σ+, B 2Σ+, and A 2Π1/2;3/2 states of CN isotopologues. The Einstein A emission coefficients generated for the A − X, B − X, and B − A transitions provide both lifetimes of the excited states as well as the B → A/X branching ratios. The ab initio permanent and transition dipole moments required are revisited within the framework of the multireference configuration interaction and of the averaged coupled-pair functional methods. An upgraded line list is provided in ExoMol format and employed to simulate intensity distribution into the high-temperature air plasma B → X and A → X spectra as well as in the rotational resolved B → X/A emission bands undergoing strong local B ∼ A ∼ X perturbations. A comparison with laboratory and astronomical spectra shows that the present line list significantly improves the treatment of both locally perturbed and highly excited rotational levels of the B ∼ A ∼ X complex.

Entanglement and iSWAP gate between molecular qubits.

Quantum computation and simulation rely on long-lived qubits with controllable interactions. Trapped polar molecules have been proposed as a promising quantum computing platform, offering scalability and single-particle addressability while still leveraging inherent complexity and strong couplings of molecules1-5. Recent progress in the single quantum state preparation and coherence of the hyperfine-rotational states of individually trapped molecules allows them to serve as promising qubits6-11, with intermolecular dipolar interactions creating entanglement12,13. However, universal two-qubit gates have not been demonstrated with molecules. Here we harness intrinsic molecular resources to implement a two-qubit iSWAP gate using individually trapped X1Σ+ NaCs molecules. By allowing the molecules to interact for 664 μs at a distance of 1.9 μm, we create a maximally entangled Bell state with a fidelity of 94(3)% in trials in which both molecules are present. Using motion-rotation coupling, we measure residual excitation of the lowest few motional states along the axial trapping direction and find them to be the primary source of decoherence. Finally, we identify two non-interacting hyperfine states within the ground rotational level in which we encode a qubit. The interaction is toggled by transferring between interacting and non-interacting states to realize an iSWAP gate. We verify the gate performance by measuring its logical truth table.

Probing the Electronic Manifold of MgCl with Millimeter-Wave Spectroscopy and Theory: (3)2Σ+ and (4)2Σ+ States.

The millimeter/submillimeter spectrum of magnesium chloride (MgCl) has been observed in two new electronic excited states, (3)2Σ+ and (4)2Σ+, using direct absorption methods. The molecule was synthesized in a mixture of Cl2, argon, and magnesium vapor. For the (3)2Σ+ state, multiple rotational transitions were measured in the v = 0 level for all six isotopologues (24Mg35Cl, 24Mg37Cl, 25Mg35Cl, 25Mg37Cl, 26Mg35Cl, and 26Mg37Cl), as well as up to v = 13 for 24Mg35Cl. For the (4)2Σ+ state, less intense spectra were recorded for 24Mg35Cl (v = 0-2). Equilibrium rotational parameters were determined for both states for 24Mg35Cl, as well as rotational constants and 25Mg hyperfine parameters for the other isotopologues. A perturbation was observed between rotational levels of the two states due to an avoided crossing. Computations were also carried out at the CASPT2 and MRCISD+Q levels, and the resulting bond lengths for (3)2Σ+ and (4)2Σ+ states agree well with the experimental values of re = 2.536 and 2.361 Å. The computations show that the (3)2Σ+ state has a double-well potential; however, the state behaves as a single well with unperturbed vibrational levels up to v = 13 due to nonadiabatic interactions with the (4)2Σ+ state.

Winter Cover Cropping in Sustainable Production Systems: Effects on Soybean and Synergistic Implications for Rhizosphere Microorganisms.

The aim of this study was to evaluate the effects of winter cover crops (CCs) on soybean agronomic performance and their implications for different physiological groups of rhizosphere microorganisms in two sustainable production systems. The production techniques for rye, peas, and oats are well known, but their suitability as CCs for soybean (organic and low-input) production needs to be examined. After two years of trials, soybean yields among the two tested winter CCs (peas and oats (P + O) and rye (R)) were statistically significant only for P + O. The soybean yield in succession to P + O as winter CCs was 3.0 t ha-1, whereas in succession to R, it was 2.7 t ha-1, and in the control plot, it was 2.6 t ha-1. The average soybean grain protein content was in the range of 40 to 41% dry matter (DM), while the oil content ranged from 20 to 22% DM. Protein and oil content primarily depends on the selected soybean variety and it is confirmed through this study that, in the studied system, we can obtain adequate grain nutritional quality. The results indicate an increase in the abundance of total bacteria, ammonifiers, and free N2-fixing bacteria in the rhizosphere, depending on the selected CCs, and differences between the tested production systems. According to this study, winter cover crops (CCs), including peas and oats (P + O) and rye (R), can be included in crop rotation for soybean. CCs can be the answer to agro-biodiversity empowerment in less diverse soybean cropping systems, along with other benefits that CCs can provide at the level of crop rotation. In addition, in almost all aspects of the study, organic production was ahead of low input. Low input is an adequate production system if there are no opportunities for organic certification and for producers who are aware of the advantages of sustainable systems, and it can also represent a transitional path towards regenerative agriculture or organic production.

Cold Molecular Ions via Autoionization below the Dissociation Limit.

Several diatomic transition metal oxides, rare-earth metal oxides, and fluorides have the unusual property that their bond dissociation energy is larger than their ionization energy. In these molecules, bound levels above the ionization energy can be populated via strong, resonant transitions from the ground state. The only relevant decay channel of these levels is autoionization; predissociation is energetically not possible and radiative decay is many orders of magnitude slower. Starting from translationally cold neutral molecules, translationally cold molecular ions can thus be produced with very high efficiency. By populating bound levels just above the ionization energy, internally cold molecular ions, exclusively occupying the lowest rotational level, are produced. This is experimentally shown here for the dysprosium monoxide molecule DyO, for which the lowest bond dissociation energy is determined to be 0.0831(6)eV above the ionization energy.

Rotational excitation of methyl mercaptan (CH3SH) in collisions with molecular hydrogen

ABSTRACT This paper presents the calculation of rate coefficients for transitions between rotational levels of the A-type and E-type levels of methyl mercaptan (CH$_3$SH), resulting from collisions with molecular hydrogen. Radiative transfer modelling requires both radiative and collisional rates to describe the rotational populations under the usual conditions in interstellar clouds where local thermodynamic equilibrium conditions do not apply. To compute the intermolecular interaction between CH$_3$SH and H$_2$, the explicitly correlated CCSD(T)-F12a coupled-cluster method that utilized a correlation-consistent aug-cc-pVTZ basis was employed. The computed energies were fit to a functional form suitable for use in scattering calculations. Rate coefficients were calculated over the temperature range from 5 to 100 K for transitions between the 110 lowest CH$_3$SH rotational levels (having energies less than 107 cm$^{-1}$ (ca. 150 K) within both the A-type and E-type manifolds caused by collisions with para- and ortho-H$_2$. The rate coefficients were obtained through time-independent quantum close coupling quantum scattering calculations utilizing the calculated potential energy surface.

Systematic Review and Meta-Analysis of Intervention Techniques in Occupational Therapy for Babies and Children with Obstetric Brachial Plexus Palsy.

(1) Background: Obstetric brachial plexus palsy (OBPP) is an unpredictable and unpreventable neurological injury, caused by shoulder dystocia during birth, that affects the brachial plexus and leads to motor and sensory deficits in the child's upper extremity. The limited literature on early therapeutic assessment of newborns with OBPP highlights a gap in specialized care that, if filled, could enhance decision-making and support timely treatment. The objective of this paper is to analyze the therapeutic intervention techniques used at an early stage and their functional impact, from the occupational therapy discipline in the treatment of the upper extremity in babies and children with OBPP. (2) Method: Systematic review design and meta-analysis. A systematic review is a comprehensive analysis of existing research on a specific topic, using rigorous methods to identify, evaluate, and synthesize studies. Meta-analysis, often part of a systematic review, combines results from multiple studies to identify overall trends and enhance reliability, providing a clearer summary of evidence. Articles that included pediatric patients (from birth to 12 years of age) with a diagnosis of OBPP were reviewed. The results of the techniques used were analyzed according to each study, with the scale or method of assessment considered by the study for the presentation of data. The articles were assessed for methodological quality using the "PEDro Validity Scale". (3) Results: A total of 2190 articles were found, with 108 analyzed and 22 fully meeting this study's standards. Fourteen had a quantitative design, while the others included clinical guidelines. The most statistically reliable intervention techniques were CIMT (constraint-induced movement therapy) and splinting (dynamic and static), with second-tier techniques like joint manipulation, NMES, early infant management education, and serial casting used when needed. This study focused on children from birth to eight years old, with assessment tools primarily measuring upper limb range of motion, external rotation, supination, and impairment levels, though bimanual activity assessment was less common. (4) Conclusions: The early implementation of the techniques that provide us with the most data are CIMT, splinting, NMES, and joint manipulation linked to health education for families. In second place, we have the use of TB infiltrations and serial casts, when the treatment of the previous techniques fails in some cases.

Measurement and assignment of J = 5 to 9 rotational energy levels in the 9070-9370cm-1 range of methane using optical frequency comb double-resonance spectroscopy.

We use optical-optical double-resonance spectroscopy with a continuous wave (CW) pump and a cavity-enhanced frequency comb probe to measure the energy levels of methane in the upper part of the triacontad polyad (P6) with higher rotational quantum numbers than previously assigned. A high-power CW optical parametric oscillator, tunable around 3000 cm-1, is consecutively locked to the P(7, A2), Q(7, A2), R(7, A2), and Q(6, F2) transitions in the ν3 band, and a comb covering the 5800-6100cm-1 range probes sub-Doppler ladder-type transitions from the pumped levels with J' = 6 to 8, respectively. We report 118 probe transitions in the 3ν3 ← ν3 spectral range with uncertainties down to 300kHz (1 × 10-5cm-1), reaching 84 unique final states in the 9070-9370cm-1 range with rotational quantum numbers J between 5 and 9. We assign these states using combination differences and by comparison with theoretical predictions from a new abinitio-based effective Hamiltonian and dipole moment operator. This is the first line-by-line experimental verification of theoretical predictions for these hot-band transitions, and we find a better agreement of transition wavenumbers with the new calculations compared to the TheoReTS/HITEMP and ExoMol databases. We also compare the relative intensities and find an overall good agreement with all three sets of predictions. Finally, we report the wavenumbers of 27 transitions in the 2ν3 spectral range, observed as V-type transitions from the ground state, and compare them to the new Hamiltonian, HITRAN2020, ExoMol, and the WKMLC line lists.

Explaining the oblate morphology of dwarf spheroidals with wave dark matter perturbations

ABSTRACT We investigate whether the oblate, spheroidal morphology of common dwarf spheroidal galaxies (dSph) may result from the slow relaxation of stellar orbits within a halo of wave dark matter ($\psi$DM) when starting from an initial disc of stars. Stellar orbits randomly walk over a Hubble time, perturbed by the pervasive ‘granular’ interference pattern of $\psi$DM, that fully modulates the dark matter density on the de Broglie scale. Our simulations quantify the level of stellar disc thickening over the Hubble time, showing that distribution of stars is predicted to become an oblate spheroid of increasing radius, that plausibly accounts for the morphology of dSph galaxies. We predict a low level of residual rotation remains after a Hubble time at the 1–3 km/s level, depending on orientation, that compares with recent claims of rotation for some well-studied local dSph galaxies. This steady internal dynamical evolution may be witnessed directly with JWST for well-resolved dwarf galaxies, appearing more oblate with look back time and tending to small discs of young stars at high redshift.

Preparation of High Vibrational States in the Entire Molecular Beam.

Preparing highly excited molecules is of great interest in chemistry, but it has long been a challenge due to the high laser power required within the narrow line width to excite a weak transition. We present a cavity-enhanced infrared excitation scheme using a milliwatt laser. As a demonstration, about 35% of CO molecules in a ground-state rotational level were excited to the highly excited v = 3 state in the entire pulsed supersonic beam, as confirmed by the depletion of molecules in the ground state. The method was also applied to excite HD molecules to the v = 2 state with a continuous-wave diode laser. This work provides a universal approach to prepare molecules in a specific quantum state, paving the way to study the chemical reaction dynamics of highly excited molecules.

Ab initio the thermodynamic properties and UV spectrum of AlCl+

AlCl+ as a potential interstellar molecule has attracted significant attention, but gaps remain in our understanding of its thermodynamic properties and spectral line intensities. This study employed the icMRCI+Q method to compute potential energy curves for the 13 Λ-S states of AlCl+. Based on these curves, spectroscopic parameters and vibrational–rotational energy levels were determined. Subsequently, partition functions were calculated over a temperature range from 50 K to 10000 K, and the thermodynamic properties were derived. Using transition dipole moments, the UV spectra for transitions from the ground state (X2Σ+) to the third excited state (22Π) were computed at 298.15 K.

The spectrum of radioactive water vapor: the H219O radio-isotopologue

The absorption spectrum of H219O, a radioactive isotopologue of the water molecule, is predicted using variational nuclear motion calculated based on a high precision potential energy function and ab initio dipole moment surface. Vibrational - rotational energy levels and wave functions, line centers and Einstein coefficients for dipole transitions are calculated. Predicted transition wavenumbers are improved by extrapolating known empirical energy levels of the stable H216O, H217O and H218O isotopologues to H219O. A line list for possible atmospheric application is presented which includes air line broadening coefficients. The calculations span a wide spectral range covering infrared and visible wavelengths, and are appropriate for temperatures up to 1000 K. Windows suitable for observing absorption by H219O are identified and comparisons made with the infrared spectra of water vapor in natural abundance, H215O and H214O.

Multi-criteria decision making for better quality indicators in µ-EDM using TiN-coated WC electrode

ABSTRACT It is highly essential to enhance the micro EDM process while machining titanium specimens. The utilization of coated electrode and adaptation of optimization algorithms in the process can enhance the material removal mechanism. In the present work, an attempt was made to find the influence of TiN coated tungsten carbide electrode in micro EDM process while machining titanium alloy specimens. It was also attempted to adopt DEAR-based optimization in the process. The TiN coating can produce lower TWR with better surface quality than uncoated tungsten carbide electrode. The capacitance has higher influential nature in µ-EDM since it controls the charging and discharging process during the spark formation across discharge gap. It was found that voltage (Level 3), capacitance (Level 3), and the tool rotation (Level 2) can create better quality measures under the prediction error of 2.3%. The optimal combination can enhance the machining accuracy with tiny craters formation.

Immediate effect of posture-dependent and weight-bearing gluteus medius exercise on muscle function in the lower extremities and dynamic knee valgus

BACKGROUND: The gluteus medius (GM) plays an important role in stabilizing the knee and preventing injury. OBJECTIVE: This study aimed to determine the immediate effects of weight-bearing gluteus medius exercises on lower-extremity muscle function and dynamic knee valgus. METHODS: Eighteen healthy adults (nine each of both sexes) performed three types of weight-bearing gluteus medius exercises (standing, mini-squat, and dead-lift), and a range of kinematic variables were tested in triplicate. Weight-supporting GM exercise consisted of three sets of 15 repetitions of the lateral band walk. The Y-balance test (YBT) and vertical single-leg jump were used as indicators of muscle function in the lower limbs. We used a video analyzer to film the dynamic knee valgus and performed a YBT for the supporting leg and landing leg following a jump. RESULTS: The height of the single-leg vertical jump and the posterolateral and total YBT scores were significantly higher in the dead-lift posture than in the standing and mini-squat postures. Motion analysis of the dead-lifts revealed high hip flexion on the supporting leg in the posterolateral direction, as determined by the YBT, with low levels of internal hip rotation on the landing leg during the one-leg vertical jump. CONCLUSION: As an immediate effect of gluteus medius exercise, the dead-lift posture facilitated single-leg vertical jump, posterolateral balance, and reduced dynamic knee valgus.

Electric Drive Units: A Set-Up for Investigating Function, Efficiency, and Dynamics

High-speed electric drive units promise improved power density and, theoretically, driving range of battery electric vehicles. An essential step of the development process is extensive testing of the drive unit on a test rig. In particular, at a high rotational speed level, experimental testing can be challenging. This paper describes a test rig for investigating the overall function of a high-speed drive unit and the transmission’s efficiency and dynamics. The high-speed drive unit developed in the Speed4E research project was the reference drive unit. The test rig is based on the concept of electrical power circulation. Thus, the test rig can be used universally for different drive unit designs and operating modes. A reaction torque measurement unit was developed to enable measurements at high rotational speeds. Simultaneously, this unit allows robust measurements at low costs. The expected measurement uncertainties of torque, rotational speed, transmission efficiency, and power losses were calculated using the Monte Carlo method. The results demonstrate that the developed torque measurement unit combines precise torque measurement with a robust design and low costs, making it competitive with state-of-the-art solutions for torque measurement at high speeds.

Dissociative recombination of rotationally cold ArH+

We have experimentally studied dissociative recombination (DR) of electronically and vibrationally relaxed ArH+ in its lowest rotational levels, using an electron-ion merged-beams setup at the Cryogenic Storage Ring. We report measurements for the merged-beams rate coefficient of ArH+ and compare it to published experimental and theoretical results. In addition, by measuring the kinetic energy released to the DR fragments, we have determined the internal state of the DR products after dissociation. At low collision energies, we find that the atomic products are in their respective ground states, which are only accessible via nonadiabatic couplings to neutral Rydberg states. Published theoretical results for ArH+ have not included this DR pathway. From our measurements, we have also derived a kinetic temperature rate coefficient for use in astrochemical models. Published by the American Physical Society 2024

Effect of rotation on negative triangularity plasmas in DIII-D

Abstract At the DIII-D tokamak, plasmas with negative triangularity (NT) have been found to have similar energy confinement times as H-mode plasmas with positive triangularity. These NT plasmas also have a stable edge that inhibits H-mode, lacks dangerous edge transients, and has naturally low impurity confinement. For these reasons, NT plasmas have the potential to be a transformative reactor scenario. To determine the importance of strong co-current neutral beam torque for NT performance at DIII-D, scans of neutral beam torque at constant neutral beam power have been performed. These scans have shown that the energy confinement time for a basic, inductive NT scenario ( q 95 ≈ 2.8 ) decreases by 16% when torque is reduced to reactor levels. This reduction in confinement can be replicated with gyrofluid modeling that isolates the role of E × B shear in the change in transport. In a separate set of discharges with lower plasma current ( q 95 ≈ 4.2 ), no significant correlation between confinement time and rotation was found. Throughout this investigation, excellent MHD stability was observed, even with very low toroidal rotation. Further, low impurity confinement was found at multiple rotation levels. Throughout the campaign, rotation near the edge was counter-current, consistent with the measurement of counter-current intrinsic edge rotation, and these observations agree with NT results from the TCV tokamak.

Strongly Rotationally Dependent Lifetimes of C2 in the 23Σg- State: Implications for Predissociation in the Vacuum Ultraviolet Region.

The radiative and photodissociative properties of the dicarbon molecule, C2, in high-lying electronic states are of utmost importance for modeling the photochemical processes that occur in various astronomical environments. Despite extensive spectroscopic studies in the last two centuries, the photodissociation properties of C2 are still largely unknown, particularly for quantum states in the vacuum ultraviolet (VUV) region. Here, the lifetimes of C2 for each individual rovibrational level in the recently identified 23Σg- state are measured for the first time using a VUV-pump-UV-probe photoionization scheme. The lifetimes are found to be strongly dependent on the rotational and vibrational quantum levels in the 23Σg- state. The strongly rotationally dependent lifetimes observed here indicate that the 23Σg- state may mainly undergo a predissociation process through couplings with nearby repulsive electronic states. The current observation could have important applications in modeling the interstellar medium and cometary comae.