Quantum Beat Method Research Articles

Quantum Beat Spectroscopy in a System of N Identical, Closely Spaced Atoms. I. N = 2

Using the example of two closely spaced localized alkaline-earth atoms, we consider the possibilities of the quantum beat method (a version of the level-crossing spectroscopy in a magnetic field) in finding two parameters characterizing the system, namely, the direction from one atom to another and the distance between them. The applicability of the method to the nanoscopy of systems of closely spaced quantum dots, vacancy centers (NV centers, etc.), and impurity atoms (molecules) in crystals is discussed.

Спектроскопия квантовых биений в системе N одинаковых, близко расположенных атомов. I. Случай N=2

AbstractUsing the example of two closely spaced localized alkaline-earth atoms, we consider the possibilities of the quantum beat method (a version of the level-crossing spectroscopy in a magnetic field) in finding two parameters characterizing the system, namely, the direction from one atom to another and the distance between them. The applicability of the method to the nanoscopy of systems of closely spaced quantum dots, vacancy centers (NV centers, etc.), and impurity atoms (molecules) in crystals is discussed.

Hyperfine structure and lifetime measurements in the 4s2nd 2D3/2 Rydberg sequence of Ga I by time-resolved laser spectroscopy

The hyperfine structure (HFS) constants of the 4s2nd 2D3/2 (n=6–18) Rydberg sequence and the 4s26p 2P3/2 level for two isotopes of 69Ga and 71Ga atoms were measured by means of the time-resolved laser-induced fluorescence (TR-LIF) technique and the quantum beat method. The observed hyperfine quantum beat spectra were analyzed and the magnetic-dipole HFS constants A as well as the electric-quadrupole HFS constants B of these levels were obtained by Fourier transform and a program for multiple regression analysis. Also using TR-LIF method radiative lifetimes of the above sequence states were determined at room temperature. The measured lifetime values range from 69 to 2279ns with uncertainties no more than 10%. To our knowledge, the HFS constants of this Rydberg sequence and the lifetimes of the 4s2nd 2D3/2 (n=10–18) levels are reported for the first time. Good agreement between our results and the previous is achieved.

Measurement of lifetimes and tensor polarizabilities of odd-parity states of atomic samarium

A systematic measurement of the lifetimes and tensor polarizabilities of the lowest-lying odd-parity levels of Sm I was performed. The lifetimes were measured by detecting time-resolved fluorescence following pulsed-laser excitation of atoms in an atomic beam; polarizabilities were measured employing the method of Stark-induced quantum beats. An analysis of the data is undertaken to find the best even-parity candidate states for an atomic electric dipole moment (EDM) measurement. For the most favorable candidate state ${(}^{7}{G}_{1}),$ the electron EDM enhancement factor is evaluated to be in the range $|R|\ensuremath{\approx}100--3800.$ Critical analysis of the present data along with earlier results in Sm shows the necessity of a term reassignment for several odd-parity states. This term reassignment is also used in an estimate of the parity-nonconserving ${}^{7}{\stackrel{\ensuremath{\rightarrow}}{{F}_{0}}}^{7}{G}_{1}$ amplitude.

G_F Landé factors of the thallium metastable 6s^26p ^2P_3/2 and first-excited 6s^27s ^2S_1/2 states determined by a pump-and-probe method of quantum beats in forward scattering: errata

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text M. Lubińska, A. Wiȩcek, J. Józefowski, J. Koperski, K. Szymaniec, and T. Dohnalik, "gF Landé factors of the thallium metastable 6s26p2P3/2 and first-excited 6s27s2S1/2 states determined by a pump-and-probe method of quantum beats in forward scattering: errata," J. Opt. Soc. Am. B 15, 1815-1815 (1998) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

G_F Landé factors of the thallium metastable 6s^26p ^2P_3/2 and first-excited 6s^27s ^2S_1/2 states determined by a pump-and-probe method of quantum beats in forward scattering

We report a first determination of gF Lande factors of the thallium metastable 6s26p 2P3/2 and first-excited 6s27s 2S1/2 states, using a pump-and-probe method of quantum beats in forward scattering. For excitation of the 62P3/2 and 72S1/2 states a Λ scheme was used. A Fourier transform produced the experimental values for gF′=1(62P3/2)↕=↕1.69±0.05,gF′=2(62P3/2)↕=↕0.97±0.05, and gF=1(72S1/2)↕=↕0.96±0.05, which coincide, within an error margin, with those obtained theoretically. The method appears to be useful in the case of metastable states in which the electric-dipole coupling to the ground state is extremely weak.

Nuclear quadrupole quantum beat spectroscopy in the electronic ground state of a polyatomic molecule by an IR-UV double resonance method

The feasibility of determining nuclear quadrupole hyperfine splittings in the ground electronic state of a polyatomic molecule using a double resonance quantum beat method has been demonstrated. Pyrimidine molecules were coherently excited into single rotational states of the S 0 20 1 (13a 1) vibrational level. The resulting hyperfine level coherences were then probed, after a variable time delay, by excitation to the S 1 O 0 level with subsequent fluorescence detection. Analysis showed that the quadrupole structure in the 20 1 (13a 1) level is similar to that previously measured in the vibrational ground state. Applications of this method and possible experimental extensions are discussed.

Determination of excitonic binding energies in symmetrically strained (GaIn)As/Ga(AsP) multiple quantum wells using quantum beat spectroscopy

We have performed sub-picosecond four-wave mixing experiments on a series of symmetrically strained (GaIn)As/Ga(AsP) multiple quantum wells. We show that these measurements allow a precise determination of exciton binding energies. One of the advantages of this quantum beat method as compared to linear optical methods is that a determination of the exciton binding energy is possible even in the presence of considerable inhomogeneous broadening. In addition, the dependence of the exciton binding energy on the strain in the (GaIn)As quantum well layers suggests that the reduced electron-hole effective mass is not influenced by the increase in strain.

Temporal optics of recoil-free gamma radiation

A discussion is given of the time-behavior of recoil-free γ-radiation passing through a resonant medium. The classical dispersion theory of Hamermesh is extended to account for different linewidths in source or absorber so that a synchrotron-radiation source can be simulated. A result, essentially the same as that of Kagan et al., follows in the limit of large source width. A review is given of the quantum beats which result from the absorption of one line of a frequency-modulation spectrum. An example is given of the measurement of second-order Doppler shift in Fe−Be by the method of quantum beats. Finally, there is a discussion of the measurement by quantum beats of the very small energy shift in a57Co−Cu source by a magnetic field.

Hyperfine interaction constants of the 10, 11 and 12 [formula omitted] states in 87Rb measured by the quantum beat method

The magnetic-dipole interaction constant A and electric-quadrupole interaction constant B were measured in a sequence of 2 D 3 2 states of 87Rb. The values obtained are ∥A(10 2 D 3 2 )∥=1.315(17) MHz , ∥A(11 2 D 3 2 )∥=0.955(11) MHz , ∥A(12 2 D 3 2 )∥=0.715(12) MHz , ∥B(10 2 D 3 2 )∥=0.070(11) MHz , B(11 2 D 3 2 )=0.049(6) MHz , and ∥B(12 2 D 3 2 )∥=0.037(8) MHz with B A >0 for all the states.

Time-resolved spectroscopic studies of the 7p 2 P states of neutral silver following VUV excitation

The radiative lifetimes of the 7p 2 P 3/2, 1/2 states of silver and the hyperfine structure of the 7p 2 P 3/2 state have been measured using pulsed laser excitation and direct observation of the induced fluorescence light decay. In order to excite this doublet, VUV radiation at 185 nm was applied, as generated by frequency tripling and anti-Stokes Raman shifting of the output of a Nd: YAG laser pumped dye laser. The lifetimes were found to be τ=255(20) ns and τ=285(25) ns for theJ=3/2 state andJ=1/2 state, respectively. The hyperfine structure of the 7p 2 P 3/2 state was measured by the quantum beat method. The magnetic dipole interaction constant for the107Ag isotope was found to bea=−4.5(2) MHZ.

Measurements of magnetic-dipole and electric-quadrupole interaction constants of the 11, 12 and 132D5/2 states in 87Rb by the quantum-beat method

Hyperfine structure in three n2D5/2 states (n=11, 12 and 13) of 87Rb was investigated by the quantum-beat method in zero magnetic field. The states of interest were excited by two-photon absorption from a single hyperfine substate (with F=1) of the ground state. The magnetic-dipole interaction constant A and the electric-quadrupole interaction constant B were obtained by analysis of the modulation frequencies of the fluorescence signals (transition n2D5/2-52P3/2). The results (MHz) are as follows: mod A(112D5/2) mod =0.361(7), mod B(112D5/2) mod =0.071(11), mod A(122D5/2) mod =0.266(9), mod B(122D5/2) mod =0.063(14), mod A(132D5/2) mod =0.20(1), mod B(132D5/2) mod =0.05(2). For all the states, A and B differ in sign. The effective lifetimes obtained as a by-product of the experiment are also presented.

Detection of solvent holes by the method of quantum beats in recombination luminescence

The present paper is concerned with a detection of solvent holes in liquid diethylsulfide, pentadecane and squalane by the method of quantum beats in recombination luminescence. The difference in g-factors in pairs (solvent) +/( p-terphenyl-d 14) - determined from the quantum beat curves fit analogous data obtained by OD ESR. The absence of beats for other studied saturated hydrocarbons testifies to that either the hole lifetime prior to its decay (or capturing by acceptor) is substantially shorter than the characteristic observation times or its ESR spectrum is insufficiently narrowed by the process of ion-molecular charge transfer.

Lifetime and hyperfine structure constants of the [formula omitted]state in 41K

The lifetime and hyperfine structure constants A and B of the 6 2D 3 2 state in 41K have been measured by the quantum beat method. The obtained values are: τ = 895(26) ns, | A| = 0.14(2) MHz, | B| = 0.05(2) MHz and B/ A > 0.

Hyperfine structures of the [formula omitted] states of 3He I

We have used the beam-foil quantum beat method to measure the hyperfine structure separations F = 3 2 − 5 2 of the 1 sn d 1 D states (n=3−8) of 3 He I . We observed the single frequency modulated decay curves of the 1 s2 p 1 P − 1 sn d 1 D transitions for times after excitation up to 50 ns, corresponding to 4−5 modulation periods. The frequency obtained (with a precision of 2–5%) are compared with other experiments and theory. The frequencies are determined mainly by the singlet-triplet energy separations and mixing factors for the He I D-states. The results agree with the same parameters obtained from other recent level-crossing measurements in strong magnetic field mixing of the singlet-triplet states.

Hyperfine structure and lifetime measurements of the 6p 2P [formula omitted] fine structure levels of gallium 69 and 71

We have determined the natural lifetime and hyperfine structure of the 6p 2P 3 2 and 6p 2P 1 2 levels of 69Ga and 71Ga. The levels were populated in an atomic beam apparatus by means of stepwise excitation using two pulsed dye lasers. The lifetimes, deduced from the fluorescence decay, are 160 ± 35 ns for the 2P 1 2 level and 150 ± 15 ns for the 2P 1 2 level. The hyperfine structure splittings were determined by means of the quantum beat method. The A factor found for 6p 2P 1 2 is 53.3 ± 0.7 MHz for 69Ga and 67.4 ± 0.7 MHz for 71Ga. The A and B factors of 6p 2P 3 2 are for 69Ga 22.4 ± 0.2 MHz and 3.2 ± 0.3 MHz, respectively, and for 71Ga 28.5 ± 0.2 MHz and 2.4 ± 0.3 MHz, respectively. The positive sign of all hfs constants, which cannot be deduced from the quantum beat measurements, is taken from the results of Hartree-Fock calculations.

Quantum beat study of the He + beam-carbon foil interaction

The quantum beat method is used to measure the HeII ( n=4) populations and coherences in an ion beam accelerated to 0.7–2.2 meV and excited by a carbon foil.

Superhigh-resolution spectroscopy based on interference of states

We describe the current methods of superhigh-resolution spectroscopy based on interference of atomic states (quantum beats and level crossing) and compare them with the methods of Doppler-free laser spectroscopy. We pay major attention to the quantum-beat method, which has been developed in recent years in connection with progress in the technique of tunable lasers, and also to the phenomenon of alignment of atoms in a gasdischarge plasma. We treat examples of application of these methods for solving problems of superhigh-resolution spectroscopy.

Hyperfine-structure study in the P sequence of23Na using quantum-beam spectroscopy

Describes use of the quantum-beat method to study hyperfine structure in the 52P3/2 and 62P3/2 states of 23Na. A pulsed dye laser, frequency-doubled into the UV region, was used to excite sodium atoms abruptly in a beam. The fluorescent light was recorded with a fast transient digitiser, interfaced to a micro-computer. Theoretical calculations using many-body perturbation theory were performed for the entire P sequence measured so far, taking polarisation and correlation effects into account separately. Very good agreement between experimental and theoretical values was obtained.

Improved [formula omitted] HFS measurement beyond the natural linewidth by beam laser quantum beats

The hyperfine splitting of 23Na I 3 2P 3 2 has been experimentally studied beyond the natural linewidth by the quantum beat method after laser excitation of a fast Na beam. A new value for the quadrupole moment has been derived: Q = (105±2) mbarn.