Rydberg level

Figure 1. Pump-probe signal for the A(v = 0) Rydberg level of NO in Ar matrices at 4 K. The plotted signal is the fluorescence in the presence of the pump only minus the fluorescence in the presence of pump and probe pulses, as a function of the time delay between them pump 195 nm, probe 784 nm. The upper curve is the cross-correlation of the pump and probe pulses.

T. P. Softley There is little doubt that in most ZEKE experiments using nanosecond lasers the Rydberg level structure is so dense that a coherent superposition of levels is populated initially, and the correct description of the dynamics should be a time-dependent one. It is possible that some control over the dynamics could be achieved using some of the methods described earlier in the conference, for example, simultaneous excitation through three-photon and one-photon transitions, using third-harmonic generation. 

The first approximation to the description of Rydberg levels treats the benzene ion-core as a monopole. This description is known not to be quantitatively accurate. Calculations which include the symmetry of the molecular ion, and the charge delocalization, lead to an energy level spectrum in much better agreement with experiment. Thus, it seems unlikely that the geometric structure of the molecular ion can be completely neglected in the study of photoionization. 

Ground state 02 and the chosen 3drr Rydberg level have the same 3Zg" symmetry but differ in their molecular orbital construction ... 

In order to test the measurements of the 2S — 8S and 2S — 8D transitions, the frequencies of the 2S — 12D intervals have also been measured in Paris [49]. This transition yields complementary information, because the 12D levels are very sensitive to stray electric fields (the quadratic Stark shift varies as n7), and thus such a measurement provides a stringent test of Stark corrections to the Rydberg levels. The frequency difference between the 2S — Y2D transitions (A 750 nm, u 399.5 THz) and the LD/Rb standard laser is about 14.2 THz, i.e. half of the frequency of the CO2/OSO4 standard. This frequency difference is bisected with an optical divider [56] (see Fig. 5). The frequency chain (see Fig. 11) is split between the LPTF and the LKB the two optical fibers are used to transfer the CO2/OSO4 standard from the LPTF to the LKB, where the hydrogen transitions are observed. This chain includes an auxiliary source at 809 nm (u 370.5 THz) such that the laser frequencies satisfy the equations ... 

Compared to the method based on the study of the 2S-3P /4/ or 2S-4P /5/ one-photon transitions, our method takes advantage of the narrow linewidths of the Rydberg levels ( , 300kHz for the 10D level). From this point of view, the 1S-2S two-photon transition with a natural linewidth of 1.3 Hz offers in principle the best experimental resolution. However, this transition is affected by the uncertainty on the IS Lamb shift, while the 2S Lamb shift has been measured with a very high precision and the nD Rydberg levels have negligible Lamb shifts. Thus the measurement of the 1S-2S frequency /6,7/ provides an experimental value of the IS Lamb shift rather than an independent value of the Rydberg constant. 

Reaction 16 was first laser induced by Happer and co-workers in a cell experiment under a multi-collision regime, which allowed, spectacularly, the product CsH to condense as powder, the so-called laser snow [144]. The dynamic picture of this reaction has emerged from a series of studies by Vetter and co-workers using a crossed-beam machine where cesium was excited to both the levels 6d [145] and 7p P [146-150]. The most interesting result concerns the reaction dynamics of cesium in the (7p Pi/2) level, which was interpreted after ah initio potential energy surface, semi-classical and quantal dynamics calculations [151 153]. The reaction of cesium in the 8p P and 9p P Rydberg levels with hydrogen molecules has also been studied [154]. 

It could also be that it is more beneficial to populate the Rydberg level in two steps, because it is easier to reach a level that is near to the ionization energy when very short wavelengths are not used. For an ionization potential of 7 eV, radiation with X < 220 nm is required, as for 1 eV = 1.6 x 10 16 erg, X is 1240 nm (because of = h c/X). In addition, the oscillator strength decreases with 2 — 1 and in the case of two-step procedures the selectivity also increases. 

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