Vibration-rotation Energy Research Articles

Analysis of measured high-resolution doublet rovibronic spectra and related line lists of 12CH and 16OH.

Detailed understanding of the energy-level structure of the quantum states as well as of the rovibronic spectra of the ethylidyne (CH) and the hydroxyl (OH) radicals is mandatory for a multitude of modelling efforts within multiple chemical, combustion, astrophysical, and atmospheric environments. Accurate empirical rovibronic energy levels, with associated uncertainties, are reported for the low-lying doublet electronic states of 12CH and 16OH, using the Measured Active Rotational-Vibrational Energy Levels (Marvel) algorithm. For 12CH, a total of 1521 empirical energy levels are determined in the primary spectroscopic network (SN) of the radical, corresponding to the following seven electronic states: X 2Π, A 2Δ, B 2Σ−, C2 Σ+, D 2Π, E 2Σ+, and F 2Σ+. The energy levels are derived from 6348 experimentally measured and validated transitions, collected from 29 sources. For 16OH, the lowest four doublet electronic states, X 2Π, A 2Σ+, B 2Σ+, and C 2Σ+, are considered, and a careful analysis and validation of 15 938 rovibronic transitions, collected from 45 sources, results in 1624 empirical rovibronic energy levels. The large set of spectroscopic data presented should facilitate the refinement of line lists for the 12CH and 16OH radicals. For both molecules hyperfine-resolved experimental transitions have also been considered, forming SNs independent from the primary SNs.

MARVEL analysis of the high-resolution rovibrational spectra of H16O35Cl

The experimentally measured high-resolution rovibrational spectra of H16O35Cl, collated from 16 sources, have been analyzed using the Marvel (Measured Active Rotational–Vibrational Energy Levels) procedure. The compilation presented, the most extensive up to now, considers a total of 21464 transitions, allowing the derivation of 6277 empirical energy levels, extending up to 17161 cm−1, corresponding to 15 vibrational parent states. Experimental transitions data from three older sources, not published explicitly in the original papers, are presented for the first time; they represent about one half of all the transitions investigated.

Experimental investigations on rotation–vibration energy transfer in H2–N2 collisions

We investigated the rotational–vibrational impact energy transfer processes in a H2–N2 gas mixture system. The stimulated Raman pumping technique was used to excite H2 molecules to the (1, 7) high rotational states. The population of the H2(1, 7) level was verified by the coherent anti-Stokes Raman (CARS) spectra, the total pressure of the mixture was maintained at 500 Torr and nitrogen with different molar ratios was filled in the sample cell. The collisional deactivation rate coefficients of the excited state H2(1, 7) with H2 and N2 were obtained by fitting the experimental data with the Stern–Volmer equation. The multi-quantum near-resonant rotational relaxation process of H2(1, 7) colliding with N2 was confirmed by the time-resolved CARS profile measurements of H2(v = 1, J = 7, 5, 3) after the excitation of H2(1, 7). The results can provide data reference for atomic and molecular physics, atomic and molecular collisions, rotation and vibration excitation calculation, etc.

Energy and momentum eigenspectrum of the Hulthén-screened cosine Kratzer potential using proper quantization rule and SUSYQM method.

Using the Qiang-Dong proper quantization rule (PQR) and the supersymmetric quantum mechanics approach, we obtain the eigenspectrum of the energy and momentum for time-independent and time-dependent Hulth'en-screened cosine Kratzer potentials. For the suggested time-independent Hulthén-screened cosine Kratzer potential (HSCKP), we solve the Schrödinger equation in D dimensions. The Feinberg-Horodecki equation for time-dependent Hulth'en-screened cosine Kratzer potential (tHSCKP) also solves. To address the inverse square term in the time-independent and time-dependent equations, we employed the Greene-Aldrich approximation approach. We were able to extract time-independent and time-dependent potentials, as well as their accompanying energy and momentum spectra. In three-dimensional space, we estimate the rotational vibrational (RV) energy spectrum for many homodimers (H2, I2, O2) and heterodimers (MnH, ScN, LiH, HCl). We also use the recently introduced formula approach to obtain the relevant eigen function. We also calculate momentum spectra for the dimers MnH and ScN. The method is compared to prior methodologies for accuracy and validity using numerical data for heterodimer LiH, HCl and homodimer I2, O2, H2. The calculated energy and momentum spectra are tabulated and analyzed.

ExoMol line lists – XLIV. Infrared and ultraviolet line list for silicon monoxide (28Si16O)

ABSTRACT A new silicon monoxide (28Si16O) line list covering infrared, visible, and ultraviolet regions called SiOUVenIR is presented. This line list extends the infrared EBJT ExoMol line list by including vibronic transitions to the $A\, {}^{1}\Pi$ and $E\, {}^{1}\Sigma ^{+}$ electronic states. Strong perturbations to the $A\, {}^{1}\Pi$ band system are accurately modelled through the treatment of six dark electronic states: $C\, {}^{1}\Sigma ^{-}$, $D\, {}^{1}\Delta$, $a\, {}^{3}\Sigma ^{+}$, $b\, {}^{3}\Pi$, $e\, {}^{3}\Sigma ^{-}$, and $d\, {}^{3}\Delta$. Along with the $X\, {}^{1}\Sigma ^{+}$ ground state, these nine electronic states were used to build a comprehensive spectroscopic model of SiO using a combination of empirical and ab initio curves, including the potential energy (PE), spin–orbit, electronic angular momentum, and (transition) dipole moment curves. The ab initio PE and coupling curves, computed at the multireference configuration interaction level of theory, were refined by fitting their analytical representations to 2617 experimentally derived SiO energy levels determined from 97 vibronic bands belonging to the X–X, E–X, and A–X electronic systems through the MARVEL (Measured Active Rotational–Vibrational Energy Levels) procedure. 112 observed forbidden transitions from the C–X, D–X, e–X, and d–X bands were assigned using our predictions, and these could be fed back into the MARVEL procedure. The SiOUVenIR line list was computed using published ab initio transition dipole moments for the E–X and A–X bands; the line list is suitable for temperatures up to 10 000 K and for wavelengths longer than 140 nm. SiOUVenIR is available from www.exomol.com and the CDS data base.

A high-resolution line list for AlO

ABSTRACT Indications of aluminium monoxide in atmospheres of exoplanets are being reported. Studies using high-resolution spectroscopy should allow a strong detection but require high-accuracy laboratory data. A marvel (measured active rotational-vibrational energy levels) analysis is performed for the available spectroscopic data on 27Al16O: 22 473 validated transitions are used to determine 6485 distinct energy levels. These empirical energy levels are used to provide an improved, spectroscopically accurate version of the ExoMol ATP line list for 27Al16O; at the same time, the accuracy of the line lists for the isotopically substituted species 26Al16O, 27Al17O, and 27Al18O is improved by correcting levels in line with the corrections used for 27Al16O. These line lists are available from the ExoMol data base at www.exomol.com.

SpectrumSDT: A program for parallel calculation of coupled rotational-vibrational energies and lifetimes of bound states and scattering resonances in triatomic systems

We present SpectrumSDT – a program for calculations of energies and lifetimes of bound rotational-vibrational states below and scattering resonances above the dissociation threshold on a global potential energy surface of a triatomic system, which may include stable molecules, weekly-bound van-der-Waals complexes, and unbound atom + diatom scattering systems. Large-amplitude vibrational motion is treated explicitly using hyper-spherical coordinates. Three options for the rotational-vibrational interaction are supported: uncoupled (symmetric top rotor), partially coupled (to include interaction between several nearest states only) and full-coupled (vibrating asymmetric-top rotor). In addition to energies and lifetimes, SpectrumSDT is able to integrate ro-vibrational wave functions over the user-defined regions of potential energy surface, which helps to classify these states. In this release of the code, SpectrumSDT is limited to ABA-type molecules with wave functions that do not extend into the regions near Eckart singularities. Program summaryProgram title: SpectrumSDTCPC Library link to program files:https://doi.org/10.17632/9gftxjs4yk.1Developer's repository link:https://github.com/IgorGayday/SpectrumSDTLicensing provisions: GNU General Public License 3 (GPL)Programming language: FortranNature of problem: Calculations of energies and lifetimes of bound rotational-vibrational states below and scattering resonances above the dissociation threshold on a global potential energy surface of a triatomic system, which may include stable molecules, weekly-bound van-der-Waals complexes, and unbound atom + diatom scattering systems.Solution method: A Hamiltonian matrix is built in APH coordinates using an optimal 2D basis set, adjusted for a given problem. A complex absorbing potential (CAP) is added to define a boundary condition for calculation of scattering resonances above the dissociation threshold. The eigenstates of the Hamiltonain matrix are found using a state-of-the-art iterative eigensolver.Restrictions: The present version is restricted to ABA-molecules and wave functions that do not extend into linear and equilateral triangle configurations.Additional comments including restriction and unusual features: Probabilities and lifetimes of the wave functions can be calculated in user-defined regions on the PES, which allows to analyze their localization properties (i.e. automatic isotopomer assignment) and obtain channel-specific lifetimes for scattering resonances.

An improved rovibrational linelist of formaldehyde, H[formula omitted]C[formula omitted

Published high-resolution rotation-vibration transitions of H212C16O, the principal isotopologue of methanal, are analyzed using the MARVEL (Measured Active Rotation-Vibration Energy Levels) procedure. The literature results are augmented by new, high-accuracy measurements of pure rotational transitions within the ground, ν3,ν4, and ν6 vibrational states. Of the 16 596 non-redundant transitions processed, which come from 43 sources including the present work, 16 403 could be validated, providing 5029 empirical energy levels of H212C16O with statistically well-defined uncertainties. All the empirical rotational-vibrational energy levels determined are used to improve the accuracy of ExoMol’s AYTY line list for hot formaldehyde. The complete list of collated experimental transitions, the empirical energy levels determined, as well as the extended and improved line list are provided as Supplementary Material.

Comments on the paper “Exact and Poisson summation thermodynamic properties for diatomic molecules with shifted Tietz potential”

Ikot et al. (Indian J Phys 93:1171, 2019) showed an analytical solution of the stationary Schrodinger equation for cesium dimers $$Cs_2$$ at the electronic state $$(3^3\Sigma _g^+)$$ with the shifted Tietz–Wei potential. We point out, however, a miscalculation in solving this equation which had led to erroneous conclusions, particularly about the energy eigenvalues, the partition function and all derived thermodynamic properties. By the way, we present the right expression of the rotational–vibrational energy which shows an excellent agreement with the experimental data.

Magnetically active terahertz wavefront control and superchiral field in a magneto-optical Pancharatnam-Berry metasurface.

Nowadays, the manipulation of the chiral light field is highly desired to characterize chiral substances more effectively, since the chiral responses of most molecules are generally weak. Terahertz (THz) waves are related to the vibration-rotational energy levels of chiral molecules, so it is significant to actively control and enhance the chirality of THz field. Here, we propose a metal/magneto-optical (MO) hybrid Pancharatnam-Berry (PB) phase structure, which can serve as tunable broadband half-wave plate and control the conversion of THz chiral states with the highest efficiency of over 80%. Based on this active PB element, MO PB metasurfaces are proposed to manipulate THz chiral states as different behaviors: beam deflector and scanning, Bessel beam, and vortex beam. Due to the magnetic-tunablibity, these proposed MO PB metasurfaces can be turned from an "OFF" to "ON" state by changing the external magnetic field. We further investigate the near-field optical chirality and the chirality enhancement factors in far field of the chiral Bessel beam and vortex beam, achieving the superchiral field with the highest chiral enhancement factor of 40 for 0th Bessel beam. These active, high efficiency and broadband chiral PB metasurfaces have promising applications for manipulation the THz chiral light and chiroptical spectroscopic techniques.

Single-molecule surface-enhanced Raman spectroscopy (SM-SERS): characteristics and analysis

Single-molecule detection (SMD), which represents the detection limit in molecular spectroscopy, has opened a new research realm in the fields of catalysis, DNA sequencing and protein analysis. Meanwhile, it provides new insights into the understanding of the molecule behaviors in a complex system. Specifically, SMD enables the quantitatively identifying of molecules accurate to single digit, provides the molecular distribution state under specific environments, and permits the in-situ observation of signal fluctuations of a single-molecule under chemical stimulus. Single-molecule surface-enhanced Raman spectroscopy (SM-SERS) is a new subject in SMD which features specific recognition of molecules by identifying the molecular chemical bonds. It is a non-destructive technology which reflects the vibration energy and rotational energy information of molecules. This technique employs metallic nanostructures to form surface plasmon resonances (SRP) under external excitation. The SPRs generate strong local electromagnetic fields ("hot spots") around metal surface to amplify the Raman signal of probe molecules in the vicinity of plasmonic materials. The giant field enhancement endows SERS superior sensitivity in trace molecule detection down to a single-molecule level. The SM-SERS offers a facile method to track the evolution of a single molecule, revealing the reaction pathways, adsorption state and distributions, and charge exchanges between the molecule and surrounding environment. Though SM-SERS has been proposed more than 20 years ago, the acquisition of SM-SERS spectra remains a bottleneck in this field due to the disability in judging the origins of these spectra. On the other hand, the lack of knowledge in analyzing SM-SERS spectra also limits the development of SM-SERS as the origins of molecule behavior at a micro level is basically unknown to the public. This review paper covers the development of SM-SERS, the past and current methods of verifying SM-SERS including the non-statistical and the bi-analyte statistical methods, the investigation into the understanding of the fluctuation characteristics of SM-SERS, as well as the related mechanisms with regard to the unique phenomena in SM-SERS such as molecule diffusion, spectral blinking and broadening. We hope this review can help the readers to relate the characteristics in SM-SERS with the origins of molecular variations during the detection, in this way to get a clear and in-depth understanding of the roadmap for SM-SERS.

The W2020 Database of Validated Rovibrational Experimental Transitions and Empirical Energy Levels of Water Isotopologues. II. H217O and H218O with an Update to H216O

The W2020 database of validated experimental transitions and accurate empirical energy levels of water isotopologues, introduced in the work of Furtenbacher et al. [J. Phys. Chem. Ref. Data 49, 033101 (2020)], is updated for H216O and newly populated with data for H217O and H218O. The H217O/H218O spectroscopic data utilized in this study are collected from 65/87 sources, with the sources arranged into 76/99 segments, and the data in these segments yield 27 045/66 166 (mostly measured) rovibrational transitions and 5278/6865 empirical energy levels with appropriate uncertainties. Treatment and validation of the collated transitions of H216O, H217O, and H218O utilized the latest, XML-based version of the MARVEL (Measured Active Rotational-Vibrational Energy Levels) protocol and code, called xMARVEL. The empirical rovibrational energy levels of H217O and H218O form a complete set through 3204 cm−1 and 4031 cm−1, respectively. Vibrational band origins are reported for 37 and 52 states of H217O and H218O, respectively. The spectroscopic data of this study extend and improve the data collated by an International Union of Pure and Applied Chemistry Task Group in 2010 [J. Tennyson et al., J. Quant. Spectrosc. Radiat. Transfer 110, 2160 (2010)] as well as those reported in the HITRAN2016 information system. Following a minor but significant update to the W2020-H216O dataset, the joint analysis of the rovibrational levels for the series H216O, H217O, and H218O facilitated development of a consistent set of labels among these three water isotopologues and the provision of accurate predictions of yet to be observed energy levels for the minor isotopologues using the combination of xMARVEL results and accurate variational nuclear-motion calculations. To this end, 9925/8409 pseudo-experimental levels have been derived for H217O/H218O, significantly improving the coverage of accurate lines for these two minor water isotopologues up to the visible region. The W2020 database now contains almost all of the transitions, apart from those of HD16O, required for a successful spectroscopic modeling of atmospheric water vapor.

Experimental energy levels of 12C14N through marvel analysis.

The cyano radical (CN) is a key molecule across many different factions of astronomy and chemistry. Accurate, empirical rovibronic energy levels with uncertainties are determined for eight doublet states of CN using the marvel (Measured Active Rotational-Vibrational Energy Levels) algorithm. 40 333 transitions were validated from 22 different published sources to generate 8083 spin-rovibronic energy levels. The empirical energy levels obtained from the marvel analysis are compared to current energy levels from the mollist line list. The mollist transition frequencies are updated with marvel energy level data which brings the frequencies obtained through experimental data up to 77.3percent from the original 11.3percent, with 92.6percent of the transitions with intensities over 10-23 cm molecule-1 at 1000K now known from experimental data. At 2000K, 100.0percent of the partition function is recovered using only marvel energy levels, while 98.2percent is still recovered at 5000K.

Diatomic molecules energy spectra for the generalized Mobius square potential model

The modified version of the generalized Mobius square (GMS) potential has been obtained by employing the dissociation energy and equilibrium bond length as explicit parameters. The potential parameters have been defined in terms of the molecular parameters. The modified GMS potential has also been used to model internuclear interaction potential curves for different states of diatomic molecules. Also, we have obtained the rotational–vibrational energy spectra of the new GMS potential model, both analytically and numerically for the different diatomic molecules. This was done by employing a Pekeris-type approximation scheme and an appropriate coordinate transformation to solve the Schrodinger equation. Our results have been compared with the experimental Rydberg–Klein–Rees (RKR) data and its corresponding average absolute deviations in terms of the dissociation energy computed. The effects of the vibrational and rotational quantum numbers on the rotational–vibrational energies for the different states of the various diatomic molecules have also been discussed. This paper has shown to be highly relevant to the studies of thermodynamic and thermochemical functions of diatomic molecules.

An update to the MARVEL data set and ExoMol line list for 12C2

ABSTRACT The spectrum of dicarbon (C2) is important in astrophysics and for spectroscopic studies of plasmas and flames. The C2 spectrum is characterized by many band systems with new ones still being actively identified; astronomical observations involve eight of these bands. Recently, Furtenbacher et al. presented a set of 5699 empirical energy levels for 12C2, distributed among 11 electronic states and 98 vibronic bands, derived from 42 experimental studies and obtained using the MARVEL (Measured Active Rotational-Vibrational Energy Levels) procedure. Here, we add data from 13 new sources and update data from 5 sources. Many of these data sources characterize high-lying electronic states, including the newly detected 3 3Πg state. Older studies have been included following improvements in the MARVEL procedure that allow their uncertainties to be estimated. These older works in particular determine levels in the C 1Πg state, the upper state of the insufficiently characterized Deslandres–d’Azambuja (C 1Πg–A 1Πu) band. The new compilation considers a total of 31 323 transitions and derives 7047 empirical (marvel) energy levels spanning 20 electronic and 142 vibronic states. These new empirical energy levels are used here to update the 8states C2 ExoMol line list. This updated line list is highly suitable for high-resolution cross-correlation studies in astronomical spectroscopy of, for example, exoplanets, as 99.4 per cent of the transitions with intensities over 10−18 cm molecule−1 at 1000 K have frequencies determined by empirical energy levels.

ROTATIONAL-VIBRATIONAL EIGEN SOLUTIONS OF THE D-DIMENSIONAL SCHRÖDINGER EQUATION FOR THE IMPROVED WEI POTENTIAL

In this present study, we have employed the techniques of exact quantization rule and ansatz solution method to obtain closed form expressions for the rotational-vibrational eigensolutions of the D-dimensional Schrödinger equation for the improved Wei potential, for cases of h′ ≠ 0 and h′ = 0. By using our derived energy equation and choosing arbitrary values of n and ℓ, we have computed the bound state rotational-vibrational energies of CO, H2 and LiH for various quantum states. The mean absolute percentage deviation (MAPD) and the Lippincott criterion ware used as a goodness-of-fit indices to compare our result with the Rydberg-Klein-Rees (RKR) and improved Tietz potential data in the literature. MAPD of 0.2862%, 0.2896% and 0.0662% relative to the RKR data for CO ware obtained. For the improved Wei and Morse potential, our computed energy eigenvalues for CO, H2 and LiH are in excellent agreement with existing results in the literature

LED based Fourier transform absorption spectroscopy of H217O in the 14900–15600 cm−1 spectral region

The vibration-rotation absorption spectrum of 17O-enriched water vapor in the range 14900–15600 cm−1 was recorded for the first time by a Fourier Transform Spectrometer coupled to a multi-pass White-type cell providing an optical path length of 34.8 m at room temperature with a spectral resolution of 0.05 cm−1 using high luminance LED (light emitting diode) light source. The high signal-to-noise ratio allowed for the accurate determination of 1047 positions of water lines, of which 661 lines were attributed to the H217O water isotopologue. The rovibrational assignment was based on new variational calculations, which allowed retrieving 285 experimental rotational-vibrational energy levels belonging to twelve vibrational states of the H217O molecule: (410), (330), (311), (231), (212), (151), (033), (052), (113), (132), (180), and (081). The 3ν1+ν2+ν3, 2ν1+3ν2+ν3 and 4ν1+ν2 vibrational bands centered, respectively, at 15325.617, 15095.166 and 15322.533 cm−1, dominate the spectrum. A detailed comparison of the H217O line intensities recorded in this study with observed literature data and with recent high-precision variational calculations showed that the calculated intensities for the (231) - (000) band are weaker by 57% than the experimental ones. The data set obtained in this study will help to improve the quality of variational calculations for water vapor.

Bound state solutions of the Schrödinger equation and its application to some diatomic molecules

We apply the supersymmetric quantum mechanics and shape invariance approach to obtain the solutions of the 3-dimensional Schrödinger equation in the presence of a newly proposed potential model called hyperbolic-sinus potential function for any ℓ-state. Rotational-vibrational energy eigenvalues of some diatomic molecules are numerically calculated. Special cases of interest of the hyperbolic-sinus potential function are also studied. Our results indicated that the energy eigenvalue is highly sensitive to the potential parameters.

Photoswitchable Photon Upconversion from Turn-on Mode Fluorescent Diarylethenes

Photon upconversion (UC) is one kind of anti-Stokes shift process, which generally requires a combination of two or more low-energy photons to produce one high-energy photon. However, another inter...

Empirical rovibrational energy levels of ammonia up to 7500 cm[formula omitted

The most recent version of the MARVEL (Measured Active Rotational-Vibrational Energy Levels) protocol and code is used to update and extend the list of accurately known empirical rovibrational energy levels of 14NH3 falling in the range of 0−7500 cm−1. Compared to an earlier similar study covering all the measured transitions of 14NH3 [22], the present investigation is limited to transitions with an upper energy level below 7500 cm−1, considers 82 sources (28 new) of transitions data, corrects several older assignments, and utilizes an improved validation procedure based partially on high-quality first-principles rovibrational energies. This study yields 4936 uniquely labelled empirical rovibrational energy levels, the set is complete up to 2413 cm−1. We confirm the overall high accuracy of the most recent “spectroscopic” (fitted) 14NH3 potential energy surface, C2018, up to 7500 cm−1. Investigation of energy values resulting from previous effective-Hamiltonian fits forms an important part of this study. It is established that previous effective-Hamiltonian fits, using high expansion orders in the Hamiltonian, are inaccurate for certain high rotational excitations of all vibrational parents considered. Employing the ground vibrational state as a test case, it is shown that the origin of the problem is that the observed 14NH3 spectroscopic network formed by rotational transitions and used for the effective-Hamiltonian fit contains floating components. A much improved effective-Hamiltonian fit is presented whereby the floating components are connected to the principal components of the spectroscopic network by carefully selected first-principles links. It is recommended that for all molecules the experimental set of transitions employed for an effective Hamiltonian fit should be checked for floating components and extra care be exercised if they exist, as in these cases the adequate reproduction of the transitions does not automatically mean that the energies derived from the effective-Hamiltonian parameters are correct as well. The connectivity problem of measured spectroscopic networks becomes more and more pronounced as the order of the Hamiltonian is increased.