Excitation of metastable levels of Li and Na using a laser-produced plasma x-ray source
This dissertation demonstrates the use of soft x rays emitted from a laser-produced plasma to excite highly energetic metastable levels in Li, Li/sup +/, and Na. These metastable levels are the energy-storage levels in several recent XUV laser proposals. Metastable ions are first produced by direct inner-shell photoionization. Neutral atoms are then collisionally excited by the ejected photoelectrons. In this case, an efficient absorber of x-rays, such as Ne, is used as the primary source of electrons while the target atom is Li. Both of these excitations have been demonstrated in Li. Excited-state population densities in excess of 10/sup -4/ cm/sup -3/ were measured in the Li/sup +/ (1s2s)/sup 1/S level at an energy of 66 eV above the Li ground state using only 50 mJ of incident laser energy. In the neutral Li case, populations as large as 2 x 10/sup -3/ cm/sup -3/ were measured in the Li(1s2s2p)/sup 4/P/sup 0/ level. Even though this level is excited only by electrons with energy greater than 57 eV, the photoionization of Ne provides such high densities of hot electrons that large metastable densities can be achieved. Sodium atoms, unlike lithium atoms are themselves efficient absorbers of x rays. Thus, excitation of neutral levels of Na requires no Ne intermediary. Populations comparable to those in the Li experiments were found in the Na(3s3p)/sup 4/D/sub 7/2/ level.
- Research Organization:
- Stanford Univ., CA (USA)
- OSTI ID:
- 5411788
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
42 ENGINEERING
LITHIUM
EXCITATION
PHOTON COLLISIONS
LITHIUM IONS
SODIUM
CATIONS
EXTREME ULTRAVIOLET RADIATION
LASER RADIATION
METASTABLE STATES
ALKALI METALS
CHARGED PARTICLES
COLLISIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
IONS
METALS
RADIATIONS
ULTRAVIOLET RADIATION
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena
420300 - Engineering- Lasers- (-1989)