Hyperfine structure optical measurements

Millimeter wave spectroscopy with a free space cell such as a Broida oven is more sensitive than lower frequency microwave spectroscopy. However, the higher J transitions monitored by millimeter wave spectroscopy often do not show the effects of hyperfine structure. In the case of CaOH and SrOH, the proton hyperfine structure was measured in beautiful pump-probe microwave optical double resonance experiments in the Steimle group [24,68], They adapted the classic atomic beam magnetic resonance experiments to work with a pulsed laser vaporization source and replaced the microwave fields in the A and C regions by optical fields (Fig. 15). These sensitive, high-precision measurements yielded a very small value for the proton Fermi contact parameter (bF), consistent with ionic bonding and a... 

With this procedure, as with the double-resonance methods in atomic physics, Zeeman and Stark splittings, hyperfine structures and A doublings in molecules can be measured with high precision, even if the observed level splittings are far less than the optical dopp-ler width. From the width of the rf resonance and from the time response of the pumped systems, orientation relaxation rates can be evaluated for individual v J") levels. Other possible applications of this promising technique have been outlined by Zare 30) Experiments to test some of these proposals are currently under investigation and their results will be reported elsewhere. 

To compare the theory of ae with experiment, it is necessary to know the value of a, which has been measured in diverse branches of physics. Currently best values of a, with relative standard uncertainty of 1 x 10-7 or less, are those based on the quantum Hall effect [32], the ac Josephson effect [25], the neutron de Broglie wavelength [33], the muonium hyperfine structure [34,35], and an absolute optical frequency measurement of the Cesium >1 line [36] ... 

Laser Physics (ILP), Novosibirsk, including different methods of frequency stabilization [3,4], measurements of hyperfine line separations or frequency intervals between absorption lines [5,6, ] and absolute optical frequency measurements [8,9,10,11]. As a result of these efforts, the Comite Consultatif des Longueurs (CCL) meeting in 1997 recommended the frequency of one particular component, the aio hyperfine structure (HFS) component of the R(56)32-0 transition, for the realization of the metre with a relative standard uncertainty of 7 x 10-11 [ ] ... 

Laser spectroscopic studies of radioactive isotopes have proved to be a valuable source in obtaining nuclear properties. The continuing developments promise a way of meeting challenge in measuring nuclear properties far from stability. It may also be so that new isotopes are discovered by optical rather than nuclear methods. The extreme high precision measurements in ionic traps make rather small nuclear effects such as hype ne anomaly interesting for tx experimental and theoretical studies. In ad(Ution the theories of hyperfine structure and isotope shift are well understood, so that detailed information on nuclear properties can be extracted. 

Resolved hyperfine structure (hfs) due to the interaction of optical electrons with the magnetic moment of the Pr nucleus (1=5/2) was observed in the spectra (Fig. 3).The measured hyperfine splittings and widths of hyperfine sublevels found from the experimental line shapes are presented in Table I. 

TiN has an X 11+ ground state and rotational transitions in the w = 0 level have been measured and analysed [69, 70] pure millimetre wave and microwave/optical double resonance methods were used, over a frequency range from 37 to 446 GHz. N hyperfine structure was observed for the two lowest rotational transitions, and the spectrum analysed using the conventional effective Hamiltonian, again expressed in cartesian form ... 

W.E. Ernst, T. Torring, Hyperfine Structure in the X S state of CaQ, measured with microwave optical polarization spectroscopy. Phys. Rev. A 27, 875 (1983)... 

The ground state hyperfine structure splitting of Be was measured by optical pumping and rf transitions between suitable (M/, Mj) substates in magnetic fields of roughly 0.7-0.8T. The respective transitions were induced with two coherent rf pulses of 0.S sec duration separated by 19 sec. This Ramsey interference method provides signal linewidths dominated by the pulse separation time. The obtained magnetic hyperfine interaction constant of... 

The ground state hyperfine structure splitting of Ba" and of was measured with microwave optical double resonance. The following description is restricted to Ba since the experiments are similar for both isotopes. Pulsed laser light tuned to one of the hyperfine components of the (6s 5i/2-6p Pi/2) resonance line at A = 493.4 nm produces a population difference between the F levels of the ground state by optical pumping. 

In a second experiment,ENDOR measurements were performed in the optically populated excited p5/2> Es/2 state of Tm " in Cap2, using the same apparatus. The ENDOR transitions were monitored via the circular polarization of the fluorescence. The authors obtained the ligand hyperfine structure constants A, = 4.83 (3) MHz and Ap = 3.59 (3) MHz of the first shell of fluorine neighbors, thus providing the first ENDOR results of an optically excited state of an impurity center. 

Because of the special properties of the exponential function the light decays with the same time constant r as the population decay. The light decay can be followed by a fast detector connected to fast, time-resolving electronics. If the excited state has a substructure, e.g. because of the Zeeman effect or hyperfine structure, and an abrupt, coherent excitation is made, oscillations (quantum beats) in the light intensity will be recorded. The oscillation frequencies correspond to the energy level separations and can be used for structure determinations. We will first discuss the generation of short optical pulses and measurement techniques for fast optical transients. 

---