Measurements of collision-induced broadening by Faraday rotation

Abstract

The influence of collisions on magneto-optical rotation spectra is considered By using a Rydberg state and nearby doublyexcited perturbers of the barium spectrum as probes, it is shown that, for a given spectral resolution, the broadening of the lines as a function of pressurecan be determined in a sensitive way at lower pressures of the perturbing gases than in conventional photoabsorption experiments. The relativefivalues of the lines (which do not change significantly in the pressure range investigated) are also accurately monitored by the same method. For the SdSp doubly excited states in Ba and the Rydberg member which lies between them, thefivalues are found to be constant to an accuracy of 5% as the pressure of rare gas is increased in the range up to 100 mb. We have also observed an intruder which can only be excited in the presence of the magnetic field.

Resonant nonlinear magneto-optical effects in atoms

“…An experimental study of collisional broadening of Rydberg spectra with the use of Faraday rotation was performed by Warry et al (1994). This work demonstrated that the resonant Faraday effect and the FS technique can be used for studies of collisional perturbations of Rydberg states with much greater precision than that of earlier photoabsorption experiments.…”

“…For example, employing synchrotron radiation and superconducting magnets, oscillator strengths of ultraviolet lines of Rydberg series of several elements were determined by Garton et al (1983), Connerade (1983), andAhmad et al (1996). An interesting experimental method, employing pulsed magnets and UV lasers, was developed by Connerade and coworkers for studies of Faraday rotation in autoionizing resonances and transitions to Rydberg states (Connerade et al, 1992;Connerade and Lane, 1988) and of collisional broadening (Warry et al, 1994).…”

Nonlinear magneto-optical rotation in calcium - theory and experiment

“…In fact, it is almost impossible to avoid this regime in experiments with laser sources, because of the wide variation in f -values of atomic transitions (as will be explained in this paper). Despite this, no explicit theoretical formalism including the effects of propagation (see our discussion below, following (19)) is yet available to interpret the results. This paper overcomes this limitation.…”

“…For all the reasons stated above, the Faraday rotation method has, in recent years, increasingly been applied as an experimental technique for the accurate determination of atomic f -values, by using synchrotron radiation [2,[9][10][11][12][13][14] which is inherently plane polarized in the plane of the orbit, or tunable laser sources of polarized light [4,[15][16][17][18][19]. It presently ranks amongst the most accurate techniques available.…”