| Summary: | 碩士 === 國立成功大學 === 物理學系碩博士班 === 97 === Using two-photon spectroscopy, Cs 6S-7D hyperfine structure has been measured and analyzed. The two-photon method, a classical nonlinear spectroscopic technique, is the best way to obtain the Doppler-free spectrum. These results can be used to determine the magnetic dipole constant A and electric quadrupole constant B to a higher precision because the linewidth is sufficiently narrow.
The first part of this thesis, the hyperfine coupling constants can be calculated from the splitting of the spectra. Secondly, in order to improve the accuracy of measurement, an acousto-optical modulator (AOM) is added in the system as a frequency marker. And then, the AOM is substituted by an electro-optical modulator (EOM) for modulating the laser frequency to mark the two-photon transitions. The frequency of EOM is calibrated by a 10MHz frequency standard which is stabilized to a cesium atomic clock. The wavelength of and TPTs are approximately 767.8 nm and 767.2 nm, respectively. In this experiment, the laser light from a ring-cavity Ti-sapphire laser was passed through a cesium vapor cell which was temperature stabilized by a homemade temperature controller. When the two-photon transition occurred, cascade violet fluorescence (7P��6S) is collected and amplified by a filtered-photomultiplier tube. The splitting intervals measured from the hyperfine spectrum were fitted with the convolution of the Lorentzian profile with the energy splitting formula by Mathemathica software. The calculated hyperfine coupling constants are as followed:
7D(5/2)： A=-1.81±0.05MHz, B=1.01±1.06MHz，
7D(3/2)： A=7.55±0.07 MHz, B=-0.62±0.87。
Chapter 6.3 is the results on the Cs 6S-8S TPTs using a circular polarized light. This study is the extension of our previous project which is the Cs 6S-8S TPTs with linear polarized light. Therefore, this part was collected as appendix. In this section, we measured the properties of TPTs (including nature line width, power broadening, and pressure broadening) and light shift and pressure shift of Cs 6S-8S.
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