Laser Diagnostics by Electrostrictive Gratings in the Gas Phase

Abstract

Over the past two decades laser induced gratings (LIGs) have been widely used to study various properties of optical media. Refractive index changes are induced by optical fields through resonant and nonresonant mechanisms, respectively. Depending on the physical mechanism which is responsible for the formation of LIGs, this technique is suited for studying different processes in the solid, liquid, and gas phase. Resonant LIGs have been used for the detection of excited state absorption in the gas phase [1] and for the measurement of ultrafast phenomena [2], Furthermore, LIGs have been applied for the measurement of flame temperature [3] and for the study of fast combustion processes [4]. Recently, two-color laser- induced gratings have been proposed as a new spectroscopic method for detecting rovibronic transitions of excited molecules in the gas phase [5,6] and for the detection of atomic hydrogen in low pressure H2/O2 flames [7].