engleski

Wavelength calibration of the CI line at 94.5 nm for comparison with quasar data

With the use of an ultra-narrow-band extreme ultraviolet laser source, tunable near 94 nm, transition wavelengths are determined for lines connecting the 1s(2)2s(2)2p(2) P-3(0, 1, 2) ground-term levels to the 1s(2)2s2p(3) S-3(1) excited level in neutral carbon at an absolute accuracy of 4x10(-8). With the determination of the zero-velocity rest-frame wavelengths these lines can be included in an analysis of a possible temporal variation of the fine-structure constant alpha from a comparison with quasar data. A value for the C-12/C-13 transition isotope shift was also obtained yielding 0.5107(13) cm(-1), in average over the three fine-structure lines. The latter measurement will allow to study isotopic evolution in the universe and test models of nuclear processes in stars.

fine-structure constant; space-time variation; neutral carbon-atom; laboratory observation; fundamental constants; isotope shifts; transitions; spectrum

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