Photodissociation cross sections of ClOOCl at 248.4 and 266 nm.
This study utilized a mass-resolved detection of ClOOCl to determine its photodissociation cross section, which is the product of the absorption cross section and dissociation quantum yield. An effusive molecular beam of ClOOCl was generated and its photodissociation probability was determined through measuring the decrease in the ClOOCl beam intensity upon laser irradiation. By comparing with a reference molecule, the absolute cross sections of ClOOCl were obtained without knowing its absolute concentration. The determined cross section of ClOOCl at 248.4 nm is (8.85+/-0.42)x10(-18) cm(2) at 200 K, significantly larger than previously reported values. The temperature dependence of the cross section was investigated at 248.4 nm in the range of 160-260 K; only a very small and negative temperature effect was observed. Because 248.4 nm is very close to the peak of the UV absorption band of ClOOCl, this work provides a new calibration point for normalizing relative absorption spectra of ClOOCl. In this work, the photodissociation cross section at 266 nm and 200 K was also reported to be (4.13+/-0.21)x10(-18) cm(2).
Lien
Chien-Yu
CY
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
Lin
Wei-Yen
WY
Chen
Hsueh-Ying
HY
Huang
Wen-Tsung
WT
Jin
Bing
B
Chen
I-Cheng
IC
Lin
Jim J
JJ