Fine structure measurement in He+, n=4. II. Intervals S-D and Lamb shift P32/-D32/

For pt.I see ibid., vol.4, no.12, L129, 1971. Electric field induced anticrossing signals are used to measure the fine structure splittings S-D of n=4 in ( 4 He) + . Extrapolation of the crossing position to zero electric field is carried out. The present results are (20145.3+or-7.8) MHz for the interval 4 2 S 1 2/-4 2 D 3/2 and (27455.4+or-7.4) MHz for the interval 4 2 S 1/2 -4 2 D 5/2 in agreement with Erickson's theoretical values of (20142.85+or-1.36) MHz and (27458.60+or-1.36) MHz respectively. The splitting 4 2 D 3/2 -4 2 D 5/2 is derived from these intervals to be (7310.1+or-15.2) MHz compared with (7315.75+or-0.02) MHz from the theory. Combining 4 2 S 1/2 -4 2 D 3/2 with 4 2 S 1/2 -4 2 P 3/2 , measured by Jacobs et al, provides a value for the Lamb shift 4 2 P 3/2 -4 2 D 3/2 of Sigma =(34.4+or-9.0) MHz compared with the theoretical value of (37.19+or-1.36) MHz.