A molecular beam study of the H+N sub 3 reaction. Product NH internal state distribution and electronic state branching ratio

Journal Article · Sat Sep 15 04:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.458735· OSTI ID:6333186

Chen, J; Dagdigian, P J ^[1]

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1. Department of Chemistry, The Johns Hopkins University, Baltimore, MD (USA)

The H+N{sub 3}{r arrow}NH({ital X} {sup 3}{Sigma}{sup {minus}},{ital a} {sup 1}{Delta}, {ital b} {sup 1}{Sigma}{sup +})+N{sub 2} reaction has been studied in a molecular beam-gas scattering arrangement in order to determine the nascent product state distribution. The NH product in specific rovibronic/fine-structure states has been detected by laser fluorescence excitation. The relative cross sections for formation of various vibrational levels in the {ital a} {sup 1}{Delta} electronic state were determined to equal 1:1.0{plus minus}0.3:1.4{plus minus}0.3:{le}1.5 for {ital v}=0 through 3, inclusive, while the {ital v}=0 to {ital v}=1 population ratio in the {ital X} {sup 3}{Sigma}{sup {minus}} state was found to be 1:0.015{plus minus}0.003. The rotational distributions in all vibronic levels were found to be characterized by temperatures near 300 K, suggestive of relaxation of the nascent rotational distributions. By comparison of the populations of a specific pair of {ital X} {sup 3}{Sigma}{sup {minus}} and {ital a} {sup 1}{Delta} state levels and with summation over the derived rovibrational distributions, an electronic state branching ratio of 3.2{plus minus}1.3 was obtained for the {ital X} {sup 3}{Sigma}{sup {minus}} to {ital a} {sup 1}{Delta} electronic state branching ratio. An upper limit of {le}0.02 was also derived for the ratio of the {ital b} {sup 1}{Sigma}{sup +} {ital v}=0 to {ital a} {sup 1}{Delta} {ital v}=0 populations. These results are compared with NH fragment distributions observed in the photodissociation of HN{sub 3}({ital {tilde X}} {sup 1}{ital A}{prime}) and with our expectations based on our fragmentary knowledge of HN{sub 3} potential energy surfaces.

• OSTI ID: 6333186
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 93:6; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AZIDES
BEAMS
BRANCHING RATIO
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL DENSITY
EXCITED STATES
HYDRAZOIC ACID
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MOLECULAR BEAMS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
RADICALS
ROTATIONAL STATES
VIBRATIONAL STATES
YIELDS