Geometry changes in molecular photoionization: The NH{sup +}{sub 3} ({tilde {ital X}}{sup 2}{ital A}{sub 2}{sup {double_prime}}){l_arrow}NH{sub 3} ({ital X}{sup 1}{ital A}{sub 1}) transition

Journal Article · Thu Feb 01 04:00:00 EST 1996 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.471647· OSTI ID:277191

Niu, B; White, M G ^[1]

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1. Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)

Single-photon threshold photoionization has been used to explore the ionization dynamics of the NH{sup +}{sub 3} ({tilde {ital X}}{sup 2}{ital A}{sub 2}{sup {double_prime}}){l_arrow}NH{sub 3} ({ital X}{sup 1}{ital A}{sub 1}) transition which involves a pyramidal-to-planar geometry change. Rotationally resolved threshold photoelectron spectra are presented for four vibrational levels of the {tilde {ital X}}{sup 2}{ital A}{sub 2}{sup {double_prime}} cation state of NH{sup +}{sub 3} corresponding to excitation of even and odd quanta of the inversion mode, {nu}{sup +}{sub 2}. The rotational state distributions exhibit strong symmetry effects imposed by the nuclear spin statistics and vibronic parity of the neutral and cation out-of-plane bend levels. The observed rotational structure is consistent with dominant {Delta}{ital K}=0 transitions and parity assignments for specific transitions show that both {ital l}=even and {ital l}=odd photoelectron final states are excited. These observations indicate that the photoelectron experiences a non-planar (pyramidal) cation potential. These results are discussed in light of previous rotationally resolved measurements on NH{sub 3} using multiphoton ionization and other systems which undergo bend excitation following ionization. {copyright} {ital 1996 American Institute of Physics.}

• Research Organization: Brookhaven National Laboratory
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 277191
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 6 Vol. 104; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
AMMONIA
CATIONS
DISTRIBUTION
EXCITED STATES
GEOMETRY
INVERSION SPECTRA
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
ROTATIONAL STATES
SYMMETRY
TRANSFORMATIONS
VIBRATIONAL STATES