Coherent Phase Control Over The Reaction Of CS₂

Scientists always pursue for controlling over the outcome of a chemical reaction in the field of reaction dynamics, and wish to control the direction and progression of a chemical reaction. The control of the molecular reaction may maximize the yield of a desired compound while reducing the yields of unwanted by-products. With the advent of lasers, which have the virtue of high monochromaticity, short pulse duration, people have achieved of control the molecular reaction by the character of the laser phase coherent. Now the field of coherent is one of the most important research areas in the physics, chemistry, biology, and so on.In this paper, we adopt the method of coherent control, which proposed by Brumer and Shapiro in 1986, by using two weak laser pulses to excite the molecule simultaneously through two distinct optical paths, and the photons transition to the same final state from the initial state. The probability of a transition from the initial state to final state equal to:We may control the yield of the product of the molecular reaction by alteringΔΦ₁₂, which is different for the phases of the two laser beams.In my experiment, w₃=355 nm, w₁=118 nm which produce by focusing a laser beam of frequency w3 into a chamber containing Xe. We alter the phase difference of two laser beams by varying the pressure of Ar. The two laser beams simultaneously interact with the CS₂ molecule. We may obtain the modulation curves by analyzing the intensities of the parent ion and fragment ions, respectively.With the coherent control principle, multiphoton ionization/dissociation mechanism and the energy levels of the CS₂ molecule, we could deduce the reaction mechanism:In addition, we obtain an experiment method: the reaction progress will be affected by moving the lens location. we future study the CS₂ cluster with the experiment method. When the 355 nm and 118 nm simultaneously interact with the CS₂ cluster, we could gain (CS₂)_n⁺(n≤8).