High-resolution uv laser spectroscopy of the 1s2s /sup 3/S/sub 1/. -->. 1snp (n = 5--79) transitions in /sup 3/He and /sup 4/He
The /sup 4/He fine structure and /sup 3/He hyperfine structure as well as the isotope shift between /sup 4/He and /sup 3/He in the 1s2s /sup 3/S/sub 1/..-->..1snp (n = 5--79) transitions have been measured using an atomic beam and an intracavity frequency-doubled coumarin ring dye laser near 270 nm. The observed 1snp /sup 3/P /sup 4/He fine structure is in agreement with (extrapolations of) existing experimental results and theoretical calculations. The 1snp /sup 3/He hyperfine structure has been analyzed using the /sup 4/He fine-structure parametrization and the Fermi-contact interaction of the screened 1s electron. For n>35 hyperfine components of the 1snp /sup 1/P levels are also excited as a consequence of hyperfine-induced singlet-triplet mixing. Calculated hyperfine splittings agree with experiment for n<20. Deviations up to 50 MHz are observed for n>20. These are shown to be due to hyperfine-induced n-mixing effects. The experimental results are excellently reproduced in a three-channel two-limit quantum-defect model without any adjustable parameter. The observed 1s2s /sup 3/S/sub 1/..-->..1snp /sup 3/P isotope shifts can be fully explained using recent mass polarization calculations for the 1s2s /sup 3/S/sub 1/ and 1snp (n = 3--8) /sup 3/P levels and confirm an isotope dependence of for the 1s2s /sup 3/S/sub 1/ level.
- Research Organization:
- Faculteit Natuurkunde en Sterrenkunde, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
- OSTI ID:
- 6068178
- Journal Information:
- Phys. Rev. A; (United States), Vol. 39:9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HELIUM 3
HYPERFINE STRUCTURE
HELIUM 4
FINE STRUCTURE
ENERGY-LEVEL TRANSITIONS
ISOTOPE EFFECTS
LASER SPECTROSCOPY
RYDBERG STATES
SPECTRAL SHIFT
ENERGY LEVELS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
EXCITED STATES
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
SPECTROSCOPY
STABLE ISOTOPES
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory