Microscopic Superfluidity in Small Helium Clusters Doped with Hydrogen Cyanide

• Author / Creator

  Dempster, Steve P

• The construction and use of a broadband Fourier-transform microwave spectrometer utilizing linear frequency sweeps will be presented along with a brief theoretical description of its operation principle. This instrument and a narrowband, cavity-based spectrometer were used to measure the high resolution microwave spectra of the J=1–0 transitions of small HeN–H12C14N, HeN–H13C14N, HeN–H12C15N, HeN–D12C14N, and HeN–D13C14N clusters produced in a supersonic jet expansion. Spectroscopic analysis revealed that the observed effective rotational constants, Beff, initially decreased with the number of the attached helium atoms before reaching a minimum at N=3 helium atoms for all isotopologues. The subsequent increase in Beff for N≥4 is indicative of the onset of microscopic superfluidity. Comparison of our experimental Beff constants with those from quantum Monte Carlo simulations reveals a nearly congruent trend in Beff up to N=6. An analysis of the hyperfine structure of the 14N containing isotopologues and the isotopic data is also provided.

• Subjects / Keywords

  • Microwave Spectroscopy
  • Hydrogen Cyanide
  • Hyperfine Structure
  • Van der Waals Complexes
  • Chirped-Pulse
  • HCN
  • Superfluid Helium

• Graduation date

  Fall 2012

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R34B2XD39

• 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.