ROTATIONAL SPECTROSCOPIC STUDY OF CYANOACETYLENE-DOPED ${ortho}$-HYDROGEN AND ${para}$-HYDROGEN CLUSTERS ((H$_{2}$)$_{N}$ - HCCCN; ${N}$ = 2 AND GREATER)
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Date
2007
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Ohio State University
Abstract
A high-resolution Fourier transform microwave spectrometer was used to measure rotational transitions of (${ortho}$H$_{2}$)$_{N}$ - HCCCN and (${para}$H$_{2}$)$_{N}$ - HCCCN (${N}$ = 2 and greater) van der Waals clusters. The clusters are prepared using a gas sample containing low concentrations of HCCCN and H$_{2}$ (normal or enriched ${para}$H$_{2}$ gas) in helium up to pressures of 40 atm. The helium supersonic jet into the spectrometer cavity produces a collision free environment where the clusters are stabilized and can be studied. Varying the backing pressures and sample concentrations controls the size distribution of the clusters. The measurement of rotational transitions corresponding to minor isotopomers of HCCCN (DCCCN, HCCC$^{15}$N, ...) aids in the assignment of the ${N}$ number. The ${N}$ number assignment also benefits from the measurement of mixed ${para}$H$_{2}$ and ${ortho}$H$_{2}$ clusters such as (${para}$H$_{2}$)(${ortho}$H$_{2}$) - HCCCN. The ${para}$H$_{2}$ containing clusters are of particular interest since ${para}$H$_{2}$ is suspected to exhibit the bulk property of superfluidity, similar to $^{4}$He.
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Author Institution: Department of Chemistry, University of Alberta, Edmonton, AB, CANADA