M. Auzinsh

Optical Polarization of Molecules

1. Angular momentum and transition dipole moment 2. Excited state angular momenta distribution 3. Ground state angular momenta polarization 4. Effect of external magnetic field on angular momenta distribution 5. General equations of motion for arbitrary J values 6. Other methods of alignment and orientation of molecules Appendix References Index.

A novel approach to quantitative spectroscopy of atoms in a magnetic field and applications based on an atomic vapor cell with L=λ

We describe the so-called λ-Zeeman method to investigate individual hyperfine transitions between Zeeman sublevels of atoms in an external magnetic field of 0.1mT–0.25T. Atoms are confined in a nanocell with thickness L=λ, where λ is the resonant wavelength (794 or 780nm for D1 or D2 line, respectively, of Rb). Narrow resonances in the transmission spectrum of the nanocell are split into several components in a magnetic field; their frequency positions and transition probabilities depend on the B field. Possible applications are described, such as magnetometers with nanometric spatial resolution and tunable atomic frequency references.

Can a Quantum Nondemolition Measurement Improve the Sensitivity of an Atomic Magnetometer

We consider the limitations due to noise (e.g., quantum projection noise and photon shot-noise) on the sensitivity of an idealized atomic magnetometer that utilizes spin squeezing induced by a continuous quantum nondemolition measurement. Such a magnetometer measures spin precession of N atomic spins by detecting optical rotation of far-detuned light. We show that for very short measurement times, the optimal sensitivity scales as N(-3/4); if strongly squeezed probe light is used, the Heisenberg limit of N-1 scaling can be achieved. However, if the measurement time exceeds tau(rel)/N(1/2) in the former case, or tau(rel)/N in the latter, where tau(rel) is the spin relaxation time, the scaling becomes N(-1/2), as for a standard shot-noise-limited magnetometer.

Dynamic effects in nonlinear magneto-optics of atoms and molecules: review

A brief review is given of topics relating to dynamical processes arising in nonlinear interactions between light and resonant systems (atoms or molecules) in the presence of a magnetic field.

Lifetimes and transition dipole moment functions of NaK low lying singlet states: Empirical and ab initio approach

The paper presents experimental D 1∏ state lifetime τv′J′ data and develops empirical and ab initio approaches concerning D 1∏ and B 1∏ lifetimes, as well as D 1∏–X 1∑+, B 1∏–X 1∑+ and D 1∏–A 1∑+ transition dipole moment functions μ(R) of the NaK molecule. Experimental D 1∏(v′,J′) state τv′J′ values for v′ varying from 1 to 22 have been obtained from experimentally measured electric radio frequency-optical double resonance (rf-ODR) signal contours. The rf-ODR signals have been produced by D 1∏←X 1∑+ laser induced optical transition and rf field (1–900 MHz) induced e–f transition within the D 1∏(v′,J′) level. The possibility to determine empirical absolute μ(R) function in a wide R range from experimental τv′J′ dependence on v′ and J′ has been demonstrated; such an approach has been applied to obtain μ(R) for the B 1∏–X 1∑+ transition on which relative intensity data are absent. The empirical D 1∏–X 1∑+μ(R) function has been considerably improved by simultaneous fitting of relative intensity and lifetime d...

Validity of rate equations for Zeeman coherences for analysis of nonlinear interaction of atoms with broadband laser radiation

In this paper we obtain the rate equations for Zeeman coherences in the broad-line approximation and steady-state balance equations directly from optical Bloch equations without the use of the perturbation theory. The broad-line approximation allows us to use the adiabatic elimination procedure in order to eliminate the optical coherences from the optical Bloch equations, but the steady-state condition allows us to derive the balance equations in a straightforward way. We compare our approach with the perturbation-theory approach as given previously and show that our approach is more flexible for analyzing various experiments. Meanwhile we also show the validity and limitations of the application of the rate equations in experiments with coherent atomic excitation when either the broad-line approximation or steady-state conditions hold. Thus we have shown the basis for modeling the coherent atomic excitation experiments by using the relatively simple rate equations, provided that certain experimental conditions hold.

High-Spatial-Resolution Monitoring of Strong Magnetic Field using Rb vapor Nanometric-Thin Cell

We have implemented the so-called λ-Zeeman technique (LZT) to investigate individual hyperfine transitions between Zeeman sublevels of the Rb atoms in a strong external magnetic field B in the range of 2500 − 5000 G (recently it was established that LZT is very convenient for the range of 10 − 2500 G). Atoms are confined in a nanometric thin cell (NTC) with the thickness L = λ, where λ is the resonant wavelength 794 nm for Rb D1 line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field with the frequency positions and transition probabilities depending on the B-field. Possible applications are described, such as magnetometers with nanometric local spatial resolution and tunable atomic frequency references.

Fluorescence of rubidium in a submicrometer vapor cell: spectral resolution of atomic transitions between Zeeman sublevels in a moderate magnetic field

It is experimentally demonstrated that use of an extremely thin cell (ETC) with the thickness of a Rb atomic vapor column of ∼400 nm allows one to resolve a large number of individual transitions between Zeeman sublevels of the D1 line of 87Rb and 85Rb in the sub-Doppler fluorescence excitation spectra in an external magnetic field of ∼200 G. It is revealed that due to the peculiarities of the Zeeman effect for different hyperfine levels of Rb, all allowed transitions between magnetic sublevels can be clearly resolved for 87RbF_g = 1 --> F_e = 1, 2 and F_g = 2 --> F_e = 1, 2 fluorescence excitation. Also, relatively good spectral resolution can be achieved for 85RbF_g = 2 --> F_e = 2, 3 fluorescence excitation. Some partial resolution of transitions between magnetic sublevels is achieved for 85RbF_g = 3 --> F_e = 2, 3 fluorescence excitation. The spectral resolution of individual transitions allows one to easily observe both linear and nonlinear Zeeman effects in the fluorescence excitation spectra obtained with the help of the ETC. In the fluorescence spectra of a cell of usual length there is no evidence of a spectral resolution of individual transitions at B ∼ 200 G. A simple magnetometer based on ETC with Rb with a submicrometer spatial resolution is described.

Hyperfine Paschen–Back regime in alkali metal atoms: consistency of two theoretical considerations and experiment

Simple and efficient λ-method and λ/2-method (λ is the resonant wavelength of laser radiation) based on a nanometric-thickness cell filled with rubidium (Rb) are implemented to study the splitting of hyperfine transitions of an Rb85 and Rb87D1 line in an external magnetic field in the range of B=0.5–0.7  T. It is experimentally demonstrated from 20 (12) Zeeman transitions allowed at low B-field in Rb85 (Rb87) spectra in the case of σ+ polarized laser radiation, only 6 (4) remain at B>0.5  T, caused by decoupling of the total electronic momentum J and the nuclear spin momentum I (hyperfine Paschen–Back regime). The expressions derived in the frame of completely uncoupled basis (J,mJ;I,mI) describe the experimental results extremely well for Rb85 transitions at B>0.6  T (that is a manifestation of hyperfine Paschen–Back regime). A remarkable result is that the calculations based on the eigenstates of the coupled (F,mF) basis, which adequately describe the system for a low magnetic field, also predict reduction of the number of transition components from 20 to 6 for Rb85 and from 12 to 4 for Rb87 spectrum at B>0.5  T. Also, the Zeeman transition frequency shifts, frequency intervals between the components and their slope versus B, are in agreement with the experiment.

Permanent electric dipoles in B 1Π and D 1Π states of NaRb: Experiment and theory

The paper presents experimentally obtained permanent electric dipole moment values (μ) in electronically excited B 1Π and D 1Π states of 23Na85Rb and 23Na87Rb isotopomer molecules for a number of vibrational and rotational levels (v′,J′). The method is based on measuring relative intensities of “forbidden” fluorescence lines appearing due to dc Stark effect induced e/f parity mixing for a particular (v′,J′)-level, combined with electric radio frequency–optical double resonance measurement of Λ-splitting energy Δe,f. The measured D 1Π state μ values are close to 6 D, representing minor changes with the vibrational level v′ varying from 0 to 12 and J′ in the region between 7 and 50, while the measured B 1Π state μ values are about 3 D for v′=4, 5 and 6. The X 1Σ+, B 1Π, and D 1Π dipole moment functions μ(R) are calculated ab initio using the many body multipartitioning perturbation theory for explicit treatment of core-valence correlations. The theoretical and experimental dipole moment estimates are in a p...