Methyl iodide photodissociation at 193 nm: The I(2P(1/2)) quantum yield

The Journal of Physical Chemistry. a
A GilchristS Taylor

Abstract

Methyl iodide photolysis at 193 nm has been studied through probing the I((2)P(1/2)-(2)P(3/2)) transition in the atomic iodine photofragment using diode laser spectroscopy. The I((2)P(1/2)) quantum yield has been determined through two different diode laser techniques and then compared. Frequency-modulated diode laser based absorption spectroscopy was used to extract nascent Doppler lineshapes from which an I((2)P(1/2)) quantum yield of unity is inferred. However when diode laser gain/absorption measurements were made, an I((2)P(1/2)) quantum yield of 0.68 ± 0.04 was found. The reason for this discrepancy is shown to lie in the diode laser gain/absorption method. Molecular iodine is found to be formed during the experiment via atomic iodine recombination and then in turn dissociates to produce both I((2)P(1/2)) and I((2)P(3/2)), thus distorting the returned quantum yield. This conclusion is supported both by the reduction of the I((2)P(1/2)) quantum yield with number of photolysis laser shots when measured using this technique and by the presence of fluoresence which is shown to have excited-state lifetimes and quenching rates that are consistent with those previously measured for the D and D' states of molecular iodine.

References

May 10, 2007·Physical Chemistry Chemical Physics : PCCP·G HancockS Taylor

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Citations

Sep 15, 2011·The Journal of Chemical Physics·D K ZaourisM N R Ashfold
Feb 2, 2011·The Journal of Chemical Physics·Aleksey B AlekseyevRobert J Buenker
Apr 3, 2012·The Journal of Chemical Physics·Daniel MurdockMichael N R Ashfold
Apr 12, 2013·The Journal of Chemical Physics·Robert J DonovanTrevor Ridley
Dec 11, 2013·The Journal of Chemical Physics·Hong Xu, S T Pratt
Jun 25, 2010·The Journal of Chemical Physics·G GitzingerL Bañares
May 7, 2015·The Journal of Physical Chemistry. a·Hong Xu, S T Pratt
Oct 8, 2009·Physical Chemistry Chemical Physics : PCCP·G HancockS Taylor
Nov 12, 2019·Physical Chemistry Chemical Physics : PCCP·Kaja SchubertMichael Martins
Sep 29, 2011·Physical Chemistry Chemical Physics : PCCP·N ThiréS T Pratt

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