Time resolved spectroscopy of krypton and xenon molecules excited by electron impact and by monochromatic synchrotron radiation

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1979

OSTI ID:5421002

Bonifield, T D

The time dependence of the fluorescence from molecular states of krypton and xenon is measured following pulsed excitation of dense pure gas samples or binary gas mixtures by a low intensity beam of high energy electrons or by monochromatized vacuum ultraviolet (vuv) synchrotron radiation. The selectivity of the initial states excited by monochromatic photons is a significant advantage over electron beam excitation for the determination of radiative lifetimes and rates for reactions involving the lowest 1/sub u/ and 0/sub u//sup +/ states of krypton and xenon. Electron beam excitation remains valuable for study of excited states which cannot be reached by photoexcitation, particularly the ionic states of the rare gases. High vibrational levels of the lowest 1/sub u/ and 0/sub u//sup +/ molecular states can be produced directly by photoexcitaion. The vibrational relaxation to the lowest vibrational levels is complete within only a few collisions in the pure rare gases, with rate constants almost as large as gas kinetic collision rates. On the other hand, the rate constants for relaxation of the 0/sub u//sup +/ state of xenon by collisions with an argon atom is more than an order of magnitude small than in pure xenon. The lowest vibrational levels of the 1/sub u/ and 0/sub u//sup +/ states radiate in the vuv with radiative lifetimes determined to be 3.4 +- 3 nsec (0/sub u//sup +/) and 264 +- 5 nsec (1/sub u/) for krypton, and 4.6 +-.3 nsec (0/sub u//sup +/) and 99 +- 2 nsec (1/sub u/) for xenon. Transitions between these states induced by collisions with ground state atoms occur with very small reaction rate constants.

• Research Organization: Rice Univ., Houston, TX (USA)
• OSTI ID: 5421002
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
BEAMS
BREMSSTRAHLUNG
COLLISIONS
ELECTROMAGNETIC RADIATION
ELECTRON BEAMS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
FLUIDS
FLUORESCENCE
GASES
KRYPTON
LEPTON BEAMS
LIFETIME
LUMINESCENCE
MOLECULE COLLISIONS
NONMETALS
PARTICLE BEAMS
RADIATIONS
RARE GASES
RELAXATION
SPECTROSCOPY
SYNCHROTRON RADIATION
TIME DEPENDENCE
VIBRATIONAL STATES
XENON