Studies Of VUV Synchrotron Radiation Photoionization And Dissociative Photoionization Of L-Valine And L-Isoleucine

In this dissertation, we study the photoionization and photodissociation of L-Valine and L-Isoleucine using synchrotron radiation VUV single photon ionization technique. With the help of density functional method(B3LYP), we analyze the experimental results and establish the dissociation channels of the amino acids.In the first chapter, we present the background and significance of photochemistry of amino acids.In the seoond chapter, we briefly introduce the history and the characteristic of synchrotron radiation, and present the advantages of synchrotron radiation and its superiority on scientific research. We also describe the application in science of the synchrotron radiation.In the third chapter, an introduction is given about the atomic and molecular physics beamline and endstation of National Synchrotron Radiation Laboratory. Firstly, the experiment setup is introduced. Secondly, the operation principle of the endstation is described. Finally, the common experimental methods, including coincidence technique, the formation mechanism of ultrasonic molecular beam, and the development and principle of mass spectrometer are discussed in details.In the fourth chapter, the theoretical methods in this thesis are briefly presented.In the fifth chapter, photoionization spectrum of L-Valine are studied in the energy region of 8-11eV coupling with the formation mechanism of ultrasonic molecular beam and principle of time of flight mass spectrometer. The pathways of major fragmentations are calculated using Gaussian 03 program calculations. Hydrogen migration is the main factor in some mechanisms, and is discussed based on the comparison of our experimental results with those predicted theoretically and experimentally.In the sixth chapter, VUV single-photon ionization of L-Isoleucine is investigated with photoionization mass spectroscopy by using synchrotron radiation. Then pathways of some major fragmentation are also predicted by B3LYP method.