M. Kunitomo

Subnanosecond relaxation of optically‐induced magnetization in aqueous solutions of transition‐metal ions

Optically‐induced magnetization in aqueous solutions of transition‐metal ions is studied by the polarization spectroscopy. From the concentration and magnetic‐field dependences of the magnetization signal in the picosecond and nanosecond regions, it is found the observed decay of the magnetization is caused by the spin cross relaxation. The quantum‐beat free‐induction‐decay signals are observed under a transverse magnetic field. Fourier transform of the observed signals gives the ESR spectra.

Group velocity of optical pulses in resonantly absorbing media

The propagation of femtosecond optical pulses in dye solutions is studied. The observed group delay of the transmitted pulses are compared with the new definition of the group velocity.

High-precision measurement of hyperfine constants of the excited state of Rb atoms by recurrent excitation

Sub-natural spectroscopy, which is based on the iterative excitation using the atomic response, is studied. The hyperfine signals of the excited state of the Rb D/sub 2/ transition were observed. Precise values of the hyperfine constants were determined.

Optical measurement of ultrashort spin-lattice relaxation time in the ground state of the thulium ion in cubic fields

Abstract Ultrashort spin-lattice relaxation times in the ground state of Tm2+ doped in CaF2 and SrF2 crystals are measured from the decay curves of the magnetization, which is created and detected by optical pulses. The temperature dependences of the spin-lattice relaxation rate 1/T1 near room temperature are deviated from the well-known T9 dependence for the Raman process. The deviation is explained consistently by a theory of the Raman process including the Debye temperature of the host crystal.