Microwave Spectroscopy Study of Methyl Salicylate and Water Clusters

  • Author / Creator
    Ghosh, Supriya
  • Details about different types of hydrogen bonding, for example strong and weak, conventional and unconventional, will be discussed. Similarly the significance of H-bonding in different fields of science will also be discussed along with theoretical descriptions. A brief description about two spectrometers, namely a cavity-based and a chirped-pulse Fourier transform spectrometer are given. These spectrometers were used to measure the high resolution microwave spectra of the methyl salicylate monomer and its clusters with water produced in a supersonic jet expansion. The mechanism for the experimentally observed dual fluorescence of methyl salicylate (MS) is a long standing research topic. Two distinctively different H-bonded methyl salicylate-water conformers, one with carbonyl O and the other with hydroxy O serving as the hydrogen-bond acceptor, were detected using chirped pulse and cavity based Fourier transform microwave spectroscopy and found to be of comparable stability. This observation provides direct experimental evidence for the previously undetected hydroxy O-bonded conformer, supporting the recently proposed new mechanism for the dual fluorescence of MS in protic solvents. An interesting interplay between the methyl internal rotation and water tunneling motions was also investigated. The existence of an unconventional O∙∙∙H-C hydrogen-bond was verified using the atoms-in-molecules theory. Thorough searches for the elusive ketoA, a high energy conformer of MS, were conducted. My results support the recent theoretical reports that only one MS conformer exists in the ground state.

  • Subjects / Keywords
  • Graduation date
    Fall 2015
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.