Orders of Magnitude and Symmetry in Molecular Spectroscopy

Oka, Takeshi

doi:10.1002/9780470749593.hrs074

Cited by 23 publications

(20 citation statements)

References 52 publications

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“…The principles of nuclear spin symmetry and parity conservation are among the most fundamental aspects of spectroscopy and reaction dynamics (Quack 1977(Quack , 1983(Quack , 1985 (see also Oka (2011): Orders of Magnitude and Symmetry in Molecular Spectroscopy and Quack (2011): Fundamental Symmetries and Symmetry Violations from High-resolution Spectroscopy, this handbook). Polyatomic molecules possessing identical nuclei with nonzero spin in symmetrically equivalent positions exist in several forms of nuclear spin isomers.…”

Section: Studies Of Nuclear Spin Symmetry Conservation In Jet Expansionsmentioning

confidence: 99%

High‐ResolutionFTIRand Diode Laser Spectroscopy of Supersonic Jets

Snels

Horká‐Zelenková

Hollenstein

et al. 2011

Handbook of High‐resolution Spectroscopy

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Fourier transform infrared (FTIR) spectrometers and tunable diode lasers in combination with a supersonic molecular beam expansion are a perfect tool for the investigation of molecules, ions, and radicals at low temperatures. The internal degrees of freedom of the molecules are adiabatically cooled to very low temperatures and thus only low-lying energy levels are populated. The reduction of the number of populated levels at low temperatures makes the assignment of the spectra much easier as compared to the congested room-temperature spectra. Under certain conditions, the Doppler linewidths are greatly reduced, corresponding to very low effective translational temperatures. Supersonic expansion also provides a suitable method for producing and investigating van der Waals clusters and hydrogen-bonded complexes. Unstable species such as radicals and ions can be efficiently produced and studied in a molecular beam. The low rotational temperature allows for the study of nuclear spin symmetry conservation or conversion between nuclear spin isomers. A molecular beam expansion can be obtained by expanding gas through a slit or a circular nozzle. Both expansion geometries can be used in combination with a multipass optical setup and with cavity ring down spectroscopy, which enhances the effective absorption path length. Cooling of the molecules can be promoted by seeding in noble gases. This article summarizes the general aspects of the experimental technique as well as current developments. To demonstrate how powerful the combination of a molecular beam expansion with tunable diode laser and FTIR spectroscopy can be, we report results on some important current examples.

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Section: Studies Of Nuclear Spin Symmetry Conservation In Jet Expansionsmentioning

confidence: 99%

High‐ResolutionFTIRand Diode Laser Spectroscopy of Supersonic Jets

Snels

Horká‐Zelenková

Hollenstein

et al. 2011

Handbook of High‐resolution Spectroscopy

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show abstract

“…the coordinatedependent expectation value of the nuclear kinetic energy operator over the ground-state electronic wavefunction, as well as relativistic corrections have been added to the Born-Oppenheimer potential energy surface. An excellent account of the various correction terms and their orders of magnitude can be found in a recent article by Oka [3]. The Born-Oppenheimer potential energy surface has been generated from ab initio points calculated by a non-standard method which makes use explicitly of the inter-electronic distance coordinate r 12 together with the electronic coordinates with respect to the three nuclei.…”

Section: Introductionmentioning

confidence: 99%

Accurate calculations and assignments of above-barrier states of up to

Alijah¹

2010

Journal of Molecular Spectroscopy

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“…1Y X X X Y jGjg, where jGj denotes the order of G (Longuet- Higgins, 1963, Quack, 1977, Bunker and Jensen, 1998, Mills and Quack, 2002, Quack, 2011, Schnell, 2011, Oka, 2011.…”

Section: Symmetry In Nuclear-motion Computationsmentioning

confidence: 99%

Exact Numerical Methods for Stationary-State-Based Quantum Dynamics of Complex Polyatomic Molecules

Császár

Fábri

Szidarovszky

2021

Molecular Spectroscopy and Quantum Dynamics

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The fourth age of quantum chemistry oers fully flexible, black-box-type protocols for the accurate and detailed study of nuclear motions, applicable equally well to semirigid, floppy, flexible, polytopic, fluxional, and quasistructural polyatomic molecular systems, including complexes and clusters. Several codes, based on advanced fourth-age protocols, have been developed for the variational (or variational-like) solution of the timeindependent nuclear-motion (rotational-vibrational) Schrödinger equation. These codes yield accurate rovibrational energy levels, wavefunctions, and to some extent quantumnumber assignments for bound, resonance, and scattering states, revealing important spectroscopic and dynamical characteristics about the systems studied. When no approximations are introduced to the kinetic energy part of the rovibrational Hamiltonian, the accuracy of the computed results, assuming the validity of the Born-Oppenheimer approximation, depends solely on the accuracy of the representation of the potential energy surface utilized during these computations. From the point of view of potential applications it is important to emphasize that the most general codes can be employed both in full and any number of reduced dimensions. Several a posteriori analysis tools are available to improve the understanding of the extreme amount of numerical results produced by the stationary-state nuclear-motion computations. As shown through a few examples, these stationary-state solutions can straightforwardly be utilized for detailed quantum-dynamics studies. The applications briefly detailed at the end of this chapter help appreciate the power of the fourth-age quantum-chemical techniques developed and available to the spectroscopic and dynamics communities.

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Orders of Magnitude and Symmetry in Molecular Spectroscopy

Cited by 23 publications

References 52 publications

High‐ResolutionFTIRand Diode Laser Spectroscopy of Supersonic Jets

High‐ResolutionFTIRand Diode Laser Spectroscopy of Supersonic Jets

Accurate calculations and assignments of above-barrier states of up to

Exact Numerical Methods for Stationary-State-Based Quantum Dynamics of Complex Polyatomic Molecules

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