Control of the parameters and composition of molecular and cluster beams by means of IR lasers
Institute of Spectroscopy, Russian Academy of Sciences, ul. Fizicheskaya 5, Troitsk, Moscow, 108840, Russian Federation
The widespread use of molecular and cluster beams in research and practice makes it necessary and relevant to develop control methods for their parameters and composition. Among the methods already developed, those based on using lasers play a considerable role. In this paper, we present results from research on the use of infrared (IR) lasers to control the parameters and composition of molecular and molecular cluster beams. We describe the methods and present research results on the neutral molecular beams acceleration due to the vibrational excitation of molecules at the nozzle outlet. We review experimental results on high-energy molecule production and the generation of molecular radicals in secondary pulsed molecular beams obtained by forming a pressure shock in front of a solid surface interacting with an intense pulsed gasdynamically cooled molecular flow, with molecules excited by the laser directly at the secondary beam source. Molecular beam kinetic energies of one to several electron volts were achieved by this method. Optimum conditions for obtaining high-energy molecules are found. Methods for determining the composition and content of pulsed molecular cluster beams are considered, as are results on the IR laser control of the composition and content of molecular cluster beams using the resonance vibrational excitation of molecules and clusters by laser radiation in the zone of gas-dynamic nozzle outlet expansion. Other methods, including laser-based ones, for controlling the velocity of beam atoms and molecules are briefly considered.