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Initial rotational distributions using a laser pump-and-probe technique
101 growth of the hologram can be measured as a function of the exciting laser light intensity in which case we obtain information on the order of the photochemical reaction. The growth rate can also be measured as a function of the laser wavelength in order to obtain a photochemical action spectrum. Further, a sequential photochemical reaction can be monitored by the observation of superimposed holograms. This is demonstrated for several experimentally observed photochemical reactions and a comparison with conventional detection methods, e.g. absorption spectroscopy, is made.
Initial rotational distributions using a laser pump-and-probe W.H.
BRECKENRIDGE
Department
of Chemistry,
technique
and H. UMEMOTO
University of Utah, Salt Lake City, UT 84112 (U.S.A.)
A laser pump-and-probe technique was used to determine the initial rotational quantum state distributions of MgH(u = 0) produced in the reaction of Mg(3s3p ‘PI) with a variety of hydrocarbons and with Hz. The distributions for all the hydrocarbons are virtually identical, peaking at N = 10 and resembling a broadened Boltzmann distribution at T = 1500 K. This is interpreted as indicating a prompt attack on individual C-H bonds at angles near 180” (i.e. abstraction). The rotational distribution for Hz is totally different and is bimodal. The predominant pathway produces increasing populations of rotational states up to N = 30; this is interpreted as resulting from a preferred angle of attack of about 90” (i.e. insertion). The minor component distribution resembles a Boltzmann distribution at T = 1000 K and is interpreted as resulting from attack at angles near 180”.
Laser photochemical initiation aud probing studies of bimolecular reaction dynamics JAMES
E. BUTLER
U.S. Naval Raearch
Laboratory,
Code 61 IO, Washington, DC 20375
(U.S.A.)
Laser photolysis and laser-probing techniques were used to determine internal energy distributions of products of the O(lD,) reactions with small hydrides. Distributions characteristic of different dynamic mechanisms for the formation of a particular product were observed together with the formation of chemically distinct products. The dynamics implications of these results are discussed.
Initial rotational distributions using a laser pump-and-probe W.H.
BRECKENRIDGE
Department
of Chemistry,
technique
and H. UMEMOTO
University of Utah, Salt Lake City, UT 84112 (U.S.A.)
A laser pump-and-probe technique was used to determine the initial rotational quantum state distributions of MgH(u = 0) produced in the reaction of Mg(3s3p ‘PI) with a variety of hydrocarbons and with Hz. The distributions for all the hydrocarbons are virtually identical, peaking at N = 10 and resembling a broadened Boltzmann distribution at T = 1500 K. This is interpreted as indicating a prompt attack on individual C-H bonds at angles near 180” (i.e. abstraction). The rotational distribution for Hz is totally different and is bimodal. The predominant pathway produces increasing populations of rotational states up to N = 30; this is interpreted as resulting from a preferred angle of attack of about 90” (i.e. insertion). The minor component distribution resembles a Boltzmann distribution at T = 1000 K and is interpreted as resulting from attack at angles near 180”.
Laser photochemical initiation aud probing studies of bimolecular reaction dynamics JAMES
E. BUTLER
U.S. Naval Raearch
Laboratory,
Code 61 IO, Washington, DC 20375
(U.S.A.)
Laser photolysis and laser-probing techniques were used to determine internal energy distributions of products of the O(lD,) reactions with small hydrides. Distributions characteristic of different dynamic mechanisms for the formation of a particular product were observed together with the formation of chemically distinct products. The dynamics implications of these results are discussed.