Rydberg laser spectroscopy

Laser spectroscopy, at the moment, is the method par excellanoe to measure R. Measurement of the Rydberg constant R is a simple matter. One measures the wavelength or frequency (the velocity of light is defined to be 299 792 1)58 m/sec) in a system, such as hydrogen, where theoretical calculations are expected to be accurate to within the experimental error. One then compares this measurement (in Hz or cm-1) with the theoretical calculation (in atomic units), thereby finding the atomic unit in Hz or cm-1. Half of the atomic unit is the Rydberg... 

The method we use is Doppler free two-photon laser spectroscopy, applied to the atomic hydrogen transitions from the metastable 2S state to the Rydberg nD states (n = 8, 10, 12) /8/. 

Fig. 2. Recent measurements of the Rydberg constant by laser spectroscopy of hydrogen and deuterium. Data points A and B are derived from the wavelength of the Balmer-a [7] or Balmer-8 line [8], observed by quenching of a beam of metastable 2S atoms with crossed dye laser beams. Data C and D are obtained by Doppler-free two-photon spectroscopy of 2S-8..12S transitions, recorded by quenching of a metastable atomic beam [9,10]. The Rydberg values E and F have been measured by Doppler-free two-photon spectroscopy of the 1S-2S transition in a gas cell [11,12],...

Table II. Some Rydberg series limits determined by stepwise laser spectroscopy.

Electron Spectro- Laser Spectroscopy LLL Rydberg Photoion. Conver- Rydberg Convergence, ... 

Fig. 2.7. Very high Rydberg states of the Ba atom recorded by laser spectroscopy using thermionic diode detection (after J.-P. Connerade et at. [27]).

Frequency measurements, which are amongst the most accurate measurements made, form a basis of, on the one hand, practical measurements of length as defined in terms of the SI metre for example, and on the other, determination of universal physical constants such as the Rydberg constant. Atomic physics lies at the heart of these measurements, providing the tools and methods of laser spectroscopy as well as the theory of atomic structure and atom-light interaction with which to interpret the results of measurements and relate them to other fields of physics. 

On the other hand, the rapid advancement of laser spectroscopy has made it possible to produce atoms in highly exited states. It has been realized, that these Rydberg atoms in uniform external fields are gateway systems for studying various aspects of chaos in... 

In this section I hope to show how the sensitivity of laser spectroscopy is exploited to obtain data on very low concentrations of atoms. In particular I will start off by considering a few laser atomic beam studies aimed at measuring optical isotope shifts and show how short-lived nuclei can be studied in this way. I shall also mention how it is possible to beat the natural linewidth and obtain supernatural spectra . The discussion of laser studies at low atomic concentrations then leads me onto consider experiments on laser cooling and trapping of atoms and ions. In this context I will also mention some experiments using the shelved electron idea to detect very weak transitions. Finally, I will say something about Rydberg atoms and the effects of atoms near metallic surfaces. 

The Stark splitting and the field ionization of very high Rydberg levels provide sensitive indicators for measuring weak electric fields. These few examples demonstrate the variety of information obtained from Rydberg state spectroscopy. More examples can be found in Sect. 9.5 and in the literature on laser spectroscopy of Rydberg states [593-597]. 

K. Harth, M. Raab, H. Hotop, Odd Rydberg spectrum of °Ne high resolution laser spectroscopy and MQDT analysis. Z. Phys. D 7, 219 (1987)... 

Previous reviews devoted to the spectroscopy of one- and two-electron Rydberg atoms by Feneuille and Jacquinot and by Fabre and Haroche do not contain any of the material presented in this chapter. However, a wealth of information concerning the general physics of Rydberg states can be found in these articles. Furthermore, brief reports of the results obtained for Ca, Sr, and Ba Rydberg states by high-resolution laser spectroscopy have recently been published by several authors. The interplay of laser... 

Although equally interesting, odd-parity Rydberg series of alkaline-earth elements have been investigated less frequently by high-resolution laser spectroscopy than the even-parity ones discussed in the previous... 

We hope that high-resolution laser spectroscopy of Rydberg states of two-electron systems, which has developed rapidly within the last three years and has contributed considerably to our knowledge of the electronic structure of such states, will continue to serve this purpose. 

M. Ayman Rydberg series of alkaline-earth atoms Ca through Ba. The interplay of laser spectroscopy and multi-channel quantum defect theory. Phys. Repts. 110, 163(1984)... 

W. Hogervorst Laser spectroscopy of Rydberg states of two-electron atoms. Comments At. Mol. Phys. 13, 69 (1983)... 

---