Infrared spectroscopy of molecules solvated in and attached to clusters of helium, hydrogen, and deuterium
Presented are the infrared spectra of SF[sub 6] monomers and dimers attached to large helium, hydrogen, and deuterium clusters. The clusters are generated in a supersonic expansion from a low temperature nozzle and the SF[sub 6] is attached to them via collisions occurring in a gas cell located on the molecular beam axis. The [nu][sub 3] vibrational mode of each species is interrogated using line tunable CO[sub 2] and N[sub 2]O lasers in a photodissociation spectrometer. The spectra are analyzed using an instantaneous dipole-induced dipole mechanism. The failure and success of this model in describing the behavior of the guest species attached to these highly quantum clusters is discussed. The results show there is an increase in the local density of the solvent around the impurity over that of the solvent's density in the bulk. This increase in density is argued to arise from the lowering of the zero-point energy of the solvent atoms in the potential field of the impurity. A second aim of this thesis is to explore the suitability of infrared spectroscopy of impurities for investigating superfluidity in these finite size systems. In the case of helium, the SF[sub 6] impurity is located on the surface of the cluster despite the apparent favorable energy gain in solvating. The expulsion of the SF[sub 6] impurity is discussed in terms of a sustained centrifugal force gradient which develops in response to the angular momentum acquired during the doping process. It is argued that, because a critical velocity below which a moving impurity can not dissipate energy into a superfluid medium exists, a fraction of the initial angular momentum will remain with the SF[sub 6] allowing it to orbit around the cluster freely. This behavior is in contrast to nonsuperfluid normal hydrogen and deuterium clusters. The possibility of a superfluid phase being present in pure parahydrogen clusters is proposed and evaluated. The use of SF[sub 6] as a probe of this phase is discussed.
- Research Organization:
- Princeton Univ., NJ (United States)
- OSTI ID:
- 5637499
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMIC CLUSTERS
SUPERFLUIDITY
SULFUR FLUORIDES
INFRARED SPECTRA
DEUTERIUM
DIMERS
HELIUM
HYDROGEN
IMPURITIES
MONOMERS
SOLVATION
VIBRATIONAL STATES
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
GASES
HALIDES
HALOGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
NONMETALS
NUCLEI
ODD-ODD NUCLEI
RARE GASES
SPECTRA
STABLE ISOTOPES
SULFUR COMPOUNDS
664200* - Spectra of Atoms & Molecules & their Interactions with Photons- (1992-)
665420 - Superfluidity- (1992-)
664500 - Special Atoms & Molecules- (1992-)