LASER-MICROWAVE SPECTROMETER AND SPECTROSCOPY OF ZINC ATOM IN TRIPLET RYDBERG STATES

PACS number: 07.57.Pt Purpose: Zinc atom in the triplet Rydberg states is the investigation subject. Purposes of the work are the following: design of a laser-microwave spectrometer intended for measuring the transition energies between the Zn I atom triplet Rydberg states, measurements of the two-photon transition frequencies between the triplet n 3 F 3 →( n + 1) 3 F 3 states, determination of quantum defect parameters for the mentioned zinc atom transitions on the obtained experimental data basis. Design/methodology/approach: A beam of neutral thermal atoms of zinc is formed inside the research chamber using the Knudsen furnace and a system of diaphragms. Then, the laser excitation system performs a selective multistep transfer of neutral atoms to the specified Rydberg states, which are initial ones for interaction with microwave radiation. The probing of the studied transitions is carried out by scanning the microwave synthesizer frequency. Microwave absorption of atoms is recorded by the magnitude of the ionization current, which is caused by electric field with exactly specified intensity (the field ionization method). The application of a recording system with a time selection of the desired signal allowed us to increase the spectrometer sensitivity by two orders of magnitude. The widespread use of optoelectronic and transformer isolations has significantly increased the spectrometer noise immunity. Findings: A laser-microwave spectrometer was created, using which, in the frequency range from 76,000 to 120,000 MHz, the measurements of the frequencies of two-photon transitions between Rydberg triplet states of the Zn I atom were made. Four microwave Rydberg transitions of n 3 F 3 →( n + 1) 3 F 3 within the principal quantum number range n from 30 to 34 were reliably dentified. The parameters of a quantum defect in the Ritz formula were obtained on the basis of experimental data analysis. Conclusions: Frequencies of two-photon F - F transitions between the triplet states with the principal quantum number n = 30–34 were measured. The values of the coefficients for calculating the quantum defect δ 0 = 0.0295152(20) and δ 2 =-0.0692(12) for the 3 F 3 terms of zinc were found from the results of the obtained data analysis. Key words: zinc atom, Rydberg states of atoms, spectrometer, laser excitation, triplet states, microwave range Manuscript submitted 18.07.2019 Radio phys. radio astron. 2019, 24(4): 272-284 REFERENCES 1. GALLAGHER, T. F., 1994. Rydberg Atoms. New York: Cambridge University Press. DOI: https://doi.org/10.1017/CBO9780511524530 2. MICHEL, L. and ZHILINSKIÍ, B. I., 2001. Rydberg states of atoms and molecules. Basic group theoretical and topological analysis. Physics Rep. vol. 341, is. 1–6, pp. 173–264. DOI: https://doi.org/10.1016/S0370-1573(00)00090-9 3. LIM, J., LEE, H. and AHN, J., 2013. Review of cold Rydberg atoms and their applications. J. 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