Self-Broadening of Optical Double Resonance Lines in Cadmium

Abstract

Collision broadening studies have been made of optical double resonance lines in cadmium. The results indicate that the collision frequency is velocity dependent, contrary to the usual theory of resonance selfbroadening. This result supports the suggestion that the broadening results from interactions involving a number of intermediate states rather than only the initial and final states of the optical transition, because of the small oscillator strength (/=0.002) for transitions between the (5s) 2 ^o ground state and the excited state in question (5s5p) 3 Pi. The cross section in this case has a l/vn 2ls velocity dependence, so the collision frequency varies as Vn 315 . Measurements show that under this assumption the self-broadening cross section for cadmium is <r coll = (1.9±0.3)X10" 12 cm70i2 2 ' 5 ,where vn is the average relative velocity in cm/sec. In the course of this work, the lifetime of the (5s,5p) 3 Pi state was redetermined and found to be (2.39±0.04)X10~6 sec.

Lifetime, Coherence Narrowing, and Hyperfine Structure of the(6s26p7s) PSaloman1, Happer2 1966Phys. Rev.84060View full textAdd to dashboardCite

“…The predictions of the theories of Bates and Damgaard and of Helliwell are listed in Tables I and III. In view of the history of conflicting results and in spite of the apparent agreement between Helliwell and Bell and King, the present work was undertaken in the hope that it would provide definitive values for these radiative properties of lead. Similar recent studies have been made of the radiative lifetimes of the low-lying excited states of the alkali, [8][9][10][11][12] alkaline-earth, [13][14][15][16] and noblegas atoms. 17 The present study is the first application of modern spectroscopic techniques to the carbon-group elements.…”

“…Further cleaning was achieved by sparking the cells with a Tesla coil before sealing them off at a pressure of about lO -6 Torr. The requirements for cell cleanliness are not as severe as for cadmium 13 and zinc 14 because of the short lifetime of the 3 Pi° state in lead.…”

The abundance of cadmium in the solar atmosphere

“…The oscillator strength of this line seems to be well determined. Using the value given by Byron et al (1964), loggf= -2.70, we find logNcd = 1.95.…”

The intercombination Cd line 326.1nm and van der Waals potential coefficients for pure Cd and Cd–inert gas systems

“…The coefficient DC 6 is sensitive to the oscillator strength. If we take the experimental value reported in the literature [18], which is equal to 2.01(3) Â 10 À3 , then DC 6 is 106.8 ± 2.3 eV Å 6 .…”