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Determination of nascent H_2 rovibrational distributions by laser induced fluorescence: applications to formaldehyde photodissociation and hydrogen exchange reactions

Citation

Parker, Garth Rockwood Jr. (1988) Determination of nascent H_2 rovibrational distributions by laser induced fluorescence: applications to formaldehyde photodissociation and hydrogen exchange reactions. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:03122013-093032947

Abstract

Individual quantum states of H_2 have been detected using the technique of Laser Induced Fluorescence. This technique is extremely sensitive, with a detection sensitivity of 6 x 10^8 states cm^(-3) in a probed volume of 0.029 cm^3 with a signal-to-noise ratio of 3. This technique is also accurate. A spectrum of room temperature H_2 had a rotational temperature of 305.8 ± 3.0 K. LIF detection of H_2 was used to study the H_2CO photodissociation reaction under essentially collision-free conditions. Following excitation of the ^τR_3 bandhead of the 2^1_04^3_0 transition at 30388.5 cm^(-1), the principal product was ortho-H_2. States as high as v = 4, J = 5 were seen. Within the v = 1 channel, the rotational distribution peaked at J = 3. Following excitation of the ^τR_4 bandhead of the 2^1_04^3_0 transition at 30396.7 cm^(-1), the principal product was para-H_2. This is the first report of the para-H_2 distribution following H_2 CO dissociation. The rotational distribution is similar to that for ortho-H_2 and peaks at J = 4 within v = 1 channel. This result contradicts a recent theoretical calculation that predicted that the para-H_2 distribution would be bimodal with a minimum at J = 6. Quantitative analysis of higher vibrational levels was hampered by a lack of spectroscopic knowledge (both transition energies and intensities) when the the B and C states perturb each other. Attempts to use LIF to study the hydrogen exchange reaction have been unsuccessful.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Kuppermann, Aron
Thesis Committee:
  • Unknown, Unknown
Defense Date:25 April 1988
Record Number:CaltechTHESIS:03122013-093032947
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:03122013-093032947
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7510
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:12 Mar 2013 17:07
Last Modified:12 Mar 2013 17:07

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