An experimental and theoretical study of the vibrationally mediated photodissociation of hydroxylamine
Abstract
We present a detailed investigation of the photodissociation of hydroxylamine following direct single-photon and vibrationally mediated two-photon excitation below 42thinsp000 cm{sup {minus}1}. In all cases the lowest dissociation channel [NH{sub 2}({tilde X}thinsp{sup 2}B{sub 1})+OH({tilde X}thinsp{sup 2}{Pi})] dominates. Single-photon dissociation at 240 nm releases most of the excess energy (20thinsp550 cm{sup {minus}1}) into relative translation (53{percent}) and NH{sub 2} internal energy (40{percent}, mostly vibrational). OH carries little internal energy (7{percent}), most of it in the form of rotational excitation. Torsional excitation during the dissociation step leads to rotational alignment of the OH fragments and a preferential population of the {Pi}(A{sup {double_prime}}) component of the lambda doublet. Both are lost after isoenergetic two-photon excitation via O{endash}H stretching overtones of NH{sub 2}OH, also leading to higher internal excitation of the NH{sub 2} fragments ({approximately}50{percent}) at the expense of relative translation. At lower total excitation energies the relative translation takes up an increasing fraction of the total excess energy ({ge}80{percent} at 5820 cm{sup {minus}1} of excess energy). The results are discussed in terms of {ital ab initio} calculations using complete active space second-order perturbation theory with augmented triple-{zeta} basis sets for the lowest excited singlet states. One- and two-dimensional potential functions explain the OHmore »
- Authors:
-
- Laboratorium fuer Physikalische Chemie, ETH Zuerich, CH-8092 Zuerich (Switzerland)
- Department of Chemistry, University of Wisconsin--Madison, Madison, Wisconsin 53706 (United States)
- Publication Date:
- OSTI Identifier:
- 289227
- Resource Type:
- Journal Article
- Journal Name:
- Journal of Chemical Physics
- Additional Journal Information:
- Journal Volume: 110; Journal Issue: 3; Other Information: PBD: Jan 1999
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 40 CHEMISTRY; NITROGEN COMPOUNDS; PERTURBATION THEORY; PHOTOLYSIS; HYDROXYLAMINE; VIBRATIONAL STATES; FRANCK-CONDON PRINCIPLE; MULTI-PHOTON PROCESSES; EXCITATION; ELECTRONIC STRUCTURE; ABSORPTION SPECTRA
Citation Formats
Luckhaus, D, Scott, J L, and Fleming Crim, F. An experimental and theoretical study of the vibrationally mediated photodissociation of hydroxylamine. United States: N. p., 1999.
Web. doi:10.1063/1.477913.
Luckhaus, D, Scott, J L, & Fleming Crim, F. An experimental and theoretical study of the vibrationally mediated photodissociation of hydroxylamine. United States. https://doi.org/10.1063/1.477913
Luckhaus, D, Scott, J L, and Fleming Crim, F. 1999.
"An experimental and theoretical study of the vibrationally mediated photodissociation of hydroxylamine". United States. https://doi.org/10.1063/1.477913.
@article{osti_289227,
title = {An experimental and theoretical study of the vibrationally mediated photodissociation of hydroxylamine},
author = {Luckhaus, D and Scott, J L and Fleming Crim, F},
abstractNote = {We present a detailed investigation of the photodissociation of hydroxylamine following direct single-photon and vibrationally mediated two-photon excitation below 42thinsp000 cm{sup {minus}1}. In all cases the lowest dissociation channel [NH{sub 2}({tilde X}thinsp{sup 2}B{sub 1})+OH({tilde X}thinsp{sup 2}{Pi})] dominates. Single-photon dissociation at 240 nm releases most of the excess energy (20thinsp550 cm{sup {minus}1}) into relative translation (53{percent}) and NH{sub 2} internal energy (40{percent}, mostly vibrational). OH carries little internal energy (7{percent}), most of it in the form of rotational excitation. Torsional excitation during the dissociation step leads to rotational alignment of the OH fragments and a preferential population of the {Pi}(A{sup {double_prime}}) component of the lambda doublet. Both are lost after isoenergetic two-photon excitation via O{endash}H stretching overtones of NH{sub 2}OH, also leading to higher internal excitation of the NH{sub 2} fragments ({approximately}50{percent}) at the expense of relative translation. At lower total excitation energies the relative translation takes up an increasing fraction of the total excess energy ({ge}80{percent} at 5820 cm{sup {minus}1} of excess energy). The results are discussed in terms of {ital ab initio} calculations using complete active space second-order perturbation theory with augmented triple-{zeta} basis sets for the lowest excited singlet states. One- and two-dimensional potential functions explain the OH product state distributions observed in different experiments in terms of the geometry relaxation of NH{sub 2}OH upon electronic excitation. Crossing between the lowest excitated A{sup {prime}} and A{sup {double_prime}} singlet states in the Franck{endash}Condon region leads to a barrier of {approximately}0.5 eV to dissociation in S{sub 1}, which dominates the photodissociation dynamics. {copyright} {ital 1999 American Institute of Physics.}},
doi = {10.1063/1.477913},
url = {https://www.osti.gov/biblio/289227},
journal = {Journal of Chemical Physics},
number = 3,
volume = 110,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 1999},
month = {Fri Jan 01 00:00:00 EST 1999}
}