Low-energy electron impact excitation of atomic oxygen: Measurement of the 3p( sup 5 P)-3s( sup 5 S) emission cross section

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5219115

Germany, G A

The 157.6 nm output from a pulsed fluorine excimer laser is focused to a cross sectional area of 1 {times} 0.1 cm in a vacuum chamber containing O{sub 2} gas at a pressure of 20 mTorr. Photodissociation of molecular oxygen produces the 2p{sup 4}({sup 3}P) and 2p{sup 4}({sup 1}D) states of atomic oxygen with unit quantum efficiency. Low-energy electron impact excitation of the 2p{sup 4}({sup 3}P) ground state is then used to produce the 3p({sup 5}P) state of atomic oxygen. Intensity measurements of the resulting 777.4 nm collisional radiation, corresponding to the 3p({sup 5}P)-2p{sup 4}({sup 5}S) transition, are placed on an absolute scale by direct comparison with the 2p{sup 4}({sup 1}D)-2p{sup 4}({sup 3}P) emission at 630.0 nm, also present as a result of the photodissociation process. The 3p({sup 5}P) excitation function peaks at approximately 16 ev and the emission cross section at 16 ev is measured to be (1.4 {plus minus} 0.4) {times} 10{sup {minus}17} cm{sup 2}. While the measured value of the 777.4 nm emission cross section reported here is approximately twenty-five percent larger than theoretical estimates, the experimental uncertainty in the present measurements is larger than this difference. In addition, the magnitude of the present measurements lends credence to theoretical estimates that the 3p({sup 5}P)-3({sup 5}S) transition in the primary cascade contributor to the O({sup 5}S) state.

• Research Organization: Arkansas Univ., Fayetteville, AR (USA)
• OSTI ID: 5219115
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
COLLISIONS
COMPARATIVE EVALUATIONS
CROSS SECTIONS
DISSOCIATION
ELECTRON COLLISIONS
ELECTRON-ATOM COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCIMER LASERS
EXCITATION
EXCITATION FUNCTIONS
FUNCTIONS
GAS LASERS
GROUND STATES
LASERS
NONMETALS
OXYGEN