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Title: Experimental and theoretical investigation of the Stark effect for manipulating cold molecules: Application to nitric oxide

Abstract

As part of an ongoing investigation of cold-molecule collisions involving nitric oxide (NO), we here theoretically assess the first- and second-order perturbation-theory approximations to the Stark shifts; such approximations have been used almost exclusively in previous published research on NO in external electric fields. We perform this assessment by comparison to Stark shifts from the corresponding nonperturbative two-state model, considering field strengths from zero to values typical of current experimental studies of cold molecules. To facilitate the future use of this model, we give expressions for the Stark energies in a generic form that can trivially be applied to any molecules in the class under consideration. To provide insight into the validity of the two-state model, we also experimentally assess the two-state Stark shifts for NO.

Authors:
; ; ;  [1]
  1. Department of Physics and Astronomy, The University of Oklahoma, 440 West Brooks Street, Norman, Oklahoma 73019-0225 (United States)
Publication Date:
OSTI Identifier:
20982148
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevA.75.023410; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; APPROXIMATIONS; CHARGES; COMPARATIVE EVALUATIONS; COOLING; CURRENTS; ELECTRIC FIELDS; LASER RADIATION; MOLECULES; NITRIC OXIDE; PERTURBATION THEORY; PHOTON-MOLECULE COLLISIONS; SPECTRAL SHIFT; STARK EFFECT

Citation Formats

Bichsel, Bryan J., Morrison, Michael A., Shafer-Ray, Neil, and Abraham, E. R. I.. Experimental and theoretical investigation of the Stark effect for manipulating cold molecules: Application to nitric oxide. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.023410.
Bichsel, Bryan J., Morrison, Michael A., Shafer-Ray, Neil, & Abraham, E. R. I.. Experimental and theoretical investigation of the Stark effect for manipulating cold molecules: Application to nitric oxide. United States. doi:10.1103/PHYSREVA.75.023410.
Bichsel, Bryan J., Morrison, Michael A., Shafer-Ray, Neil, and Abraham, E. R. I.. Thu . "Experimental and theoretical investigation of the Stark effect for manipulating cold molecules: Application to nitric oxide". United States. doi:10.1103/PHYSREVA.75.023410.
@article{osti_20982148,
title = {Experimental and theoretical investigation of the Stark effect for manipulating cold molecules: Application to nitric oxide},
author = {Bichsel, Bryan J. and Morrison, Michael A. and Shafer-Ray, Neil and Abraham, E. R. I.},
abstractNote = {As part of an ongoing investigation of cold-molecule collisions involving nitric oxide (NO), we here theoretically assess the first- and second-order perturbation-theory approximations to the Stark shifts; such approximations have been used almost exclusively in previous published research on NO in external electric fields. We perform this assessment by comparison to Stark shifts from the corresponding nonperturbative two-state model, considering field strengths from zero to values typical of current experimental studies of cold molecules. To facilitate the future use of this model, we give expressions for the Stark energies in a generic form that can trivially be applied to any molecules in the class under consideration. To provide insight into the validity of the two-state model, we also experimentally assess the two-state Stark shifts for NO.},
doi = {10.1103/PHYSREVA.75.023410},
journal = {Physical Review. A},
number = 2,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • The doublet and quartet states of the diatomic dication NO/sup 2 +/ have been investigated by ab initio CI calculations. Energies and tunnelling lifetimes of all rotational-vibrational levels, of the two quasi-bound states thus characterized, have been calculated. Some new experimental results are presented, and an extensive discussion is given of known theoretical results vis-a-vis experimental information available for NO/sup 2 +/. The latter include data from electron-impact ionization onsets, Auger spectroscopy, double-charge-transfer spectroscopy, translational energy loss spectroscopy, and measurements of kinetic energy release accompanying predissociation over a wide range of time scales.
  • Using a low power, rapid (nsec) pulse-modulated quantum cascade (QC) laser, collective coherent effects in the 5 {micro}m spectrum of nitric oxide have been demonstrated by the observation of sub-Doppler hyperfine splitting and also Autler-Townes splitting of Doppler broadened lines. For nitrous oxide, experiments and model calculations have demonstrated that two main effects occur with ulsemodulated (chirped) quantum cascade lasers: free induction decay signals, and signals induced by rapid passage during the laser chirp. In the open shell molecule, NO, in which both {Lambda}-doubling splitting and hyperfine structure occur, laser field-induced coupling between the hyperfine levels of the two {Lambda}-doubletmore » components can induce a large AC Stark effect. This may be observed as sub-Doppler structure, field-induced splittings, or Autler-Townes splitting of a Doppler broadened line. These represent an extension of the types of behaviour observed in the closed shell molecule nitrous oxide, using the same apparatus, when probed with an 8 {micro}m QC laser.« less
  • A large AC Stark effect has been observed when nitric oxide, at low pressure in a long optical path (100 m) Herriot cell, is subjected to infrared radiation from a rapidly swept, continuous wave infrared quantum cascade laser. As the frequency sweep rate of the laser is increased, an emission signal induced by rapid passage, occurs after the laser frequency has passed through the resonance of a molecular absorption line. At very high sweep rates a laser field-induced splitting of the absorptive part of the signal is observed, due to the AC Stark effect. This splitting is related to themore » Autler-Townes mixing of the hyperfine transitions, which lie within the lambda doublet components of the transition, under the Doppler broadened envelope.« less
  • The pressure dependence of the ac Stark effect for the two-photon A/sup 2/..sigma../sup +/, v' = 0left-arrowX /sup 2/Pi, v'' = 0 transition in NO is studied by using laser-induced fluorescence. Contrary to earlier results obtained by using multiphoton-ionization detection for the same transition (Demaray et al., J. Chem. Phys. 75, 5772 (1980); Li and Johnson, Phys. Rev. A 37, 3801 (1988)), the ac-Stark-broadened linewidth is constant for pressures between 2 x 10/sup -4/ and 10 Torr. Possible explanations for this difference are discussed.
  • Because NO is a primary byproduct in the combustion of fossil fuels, understanding its atmospheric chemistry is important; therefore, reactions of NO with atmospheric components such as ozone may provide new information to minimize pollution of this type. In addition to the atmospheric chemistry of NO, it is important to understand the interactions of NO with any number of transition metals and transition metal surfaces because these catalytic materials are finding widespread use in industry for the removal of NO and other ozone-depleting gases from industrial effluent. Laser-ablated Zr, Hf, and Th atoms react with NO to form the bentmore » NMO insertion products. These favorable reactions proceed on annealing to 21--24 K. The NMO molecules are characterized by isotopic substitution and M{single_bond}O stretching modes at 844.2, 855.2, and 760.3/cm and M{single_bond}N stretching modes at 673.3, 685.3, and 697.3/cm, respectively. The increase in bond stretching frequencies from Zr to Hf is due to relativistic contraction not found from Hf to Th. The BP86 functional and averaged relativistic effective potentials for Zr and Hf predict bent {sup 2}A{prime} states and observed frequencies within 1--3% and the isotopic shifts within 2/cm.« less