Comments on ''laser-excited fluorescence of the hydroxyl radical: relaxation coefficients at atmospheric pressure'' by C. Y. Chan, R. J. O'Brien, T. M. Hard, and T. B. Cook
- Resource Type
- Journal Article
- Authors
- Source
- J. Phys. Chem.; (United States); 88:13
- Subject
- 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY HYDROXYL RADICALS
EXCITATION
ACCURACY
ATMOSPHERIC CHEMISTRY
CROSS SECTIONS
FLUORESCENCE
FLUORESCENCE SPECTROSCOPY
LASER RADIATION
LOW PRESSURE
OXYGEN
PHOTOCHEMISTRY
PRESSURE DEPENDENCE
RELAXATION
TIME DEPENDENCE
CHEMISTRY
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION SPECTROSCOPY
ENERGY-LEVEL TRANSITIONS
LUMINESCENCE
NONMETALS
RADIATIONS
RADICALS
SPECTROSCOPY 400500* -- Photochemistry
400600 -- Radiation Chemistry
- Language
- English
The comment points out discrepancies and inconsistencies in conclusions drawn about results by Chan et. al. Data published by a number of other independent experimenters support the supposition that the quenching cross sections of hydroxyl radicals are pressure independent at atmospheric pressure. Data, which led Chan et. al. to claim the existence of a pressure dependence, were measured in oxygen at pressures of 40 torr and higher. At 40 torr, the fluorescence lifetime is already shorter than their laser pulse width by a factor of ca 35. The authors need to improve their temporal resolution by at least one order of magnitude to improve accuracy of measurements. For measurements at higher pressures, still faster excitation and detection will be necessary. 7 references.