Photoelectron spectroscopy of negative ions: Energy and angle-resolved measurements

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6098957

Thompson, J S

A crossed laser negative ion beams apparatus has been used to investigate both Ca{sup {minus}} and He{sup {minus}} ions. The fast negative ion beam was perpendicularly crossed with a photon beam from a flashlamp-pumped dye laser. Experimental evidence is presented to show that Ca{sup {minus}} is a stable ion and is formed in the (4s{sup 2}4p) {sup 2}P state. This result represents the first report of a stable negative ion for a Group IIA element. The structure of Ca{sup {minus}} was determined by means of photoelectron detachment spectroscopy. Kinematic effects associated with a fast moving ion beam were exploited, in a novel way, in these experiments. The electron affinity of Ca was measured to be 0.043{plus minus}0.007eV, which is in good agreement with recent calculations. Energy-and angle-resolved spectroscopy measurements have been used to study, for the first time, the spectral dependence of the angular distributions of electrons photodetached from a beam of He{sup {minus}} ions. Photoelecton angular distributions were measured by varying the angle between the electric field vector of the linearly polarized laser beam and the fixed collection direction. In the spectral range of the measurements, 1.775-2.456 eV, photodetachment into either the He(1s2s) {sup 3}S + e or He(1s2p) {sup 3}P + e continua is allowed. These competing channels were resolved and the spectral dependence of the angular distributions were measured for each case.

• Research Organization: Tennessee Univ., Knoxville, TN (USA)
• OSTI ID: 6098957
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
ANIONS
BEAMS
CALCIUM IONS
CHARGED PARTICLES
DISTRIBUTION
DYE LASERS
ELECTRON DETACHMENT
ELECTRON SPECTROSCOPY
ENERGY LEVELS
HELIUM IONS
ION BEAMS
IONS
LASERS
LIQUID LASERS
PARTICLE KINEMATICS
PHOTOELECTRON SPECTROSCOPY
PHOTON BEAMS
SPECTROSCOPY