Optical-rf Double Resonance Research Articles

Optical hole burning and optical-RF double resonance studies in CaF 2:Pr 3+:O 2-

A C 3v centre in oxygenated CaF 2:Pr 3+ has been studied by optical hole burning and optical-RF double resonance techniques. The hole burning takes place due to the population redistribution between hyperfine and superhyperfine levels associated with the 4H 3(E)→ 1D 2(E) electronic transition of Pr 3+. Ground state hyperfine splittings are observed as antiholes at multiples of 4.1 GHz and side holes at 4.08 GHz are observed only in the presence of a magnetic field. A three-line superhyperfine spectrum in the 1–25 MHz range has been observed by optical-RF double resonance technique, corresponding to three sets of inequivalent nearest neighbour F nuclei. These results together with the low resolution electronic Zeeman spectrum have been used to confirm the symmetry of the centre, and to determine the hyperfine interaction parameters in the ground and the excited state.

Hyperfine structure and nuclear and electronic Zeeman effect of theD21↔H43transition ofPr3+:CaF2

The electronic and nuclear magnetic moments and the effective nuclear-quadrupole interactions of the ground and excited states of the 2940.97-\AA{} $^{1}D_{2}\ensuremath{\leftrightarrow}^{3}H_{4}$ transition of ${\mathrm{Pr}}^{3+}$ ions in tetragonal sites of Ca${\mathrm{F}}_{2}$ have been measured using spectral hole burning, rf- and microwave-optical double-resonance and laser-excited fluorescence-excitation spectroscopy. The ground state is an electronic doublet of $E$ symmetry whose electronic magnetic moment tensor is given by $\frac{{g}_{\ensuremath{\parallel}}\ensuremath{\beta}}{h}=5.44$ MHz/G and ${g}_{\ensuremath{\perp}}=0$. The nuclear magnetic splitting factor parallel to the ${C}_{4}$ axis is $\frac{{\ensuremath{\gamma}}_{\ensuremath{\parallel}}^{g}}{2\ensuremath{\pi}}=1.65$ kHz/G, and the effective quadrupole coupling constant ${D}^{g}=+1.39$ MHz is dominated by pseudoquadrupole effects. The excited state is an electronic singlet, and rf-optical double resonance was used to determine the nuclear Zeeman splittings and obtain a very precise value for the nuclear magnetic moment of $^{141}\mathrm{Pr}$, i.e., $4.2754(5){\ensuremath{\mu}}_{N}$. For fields parallel to the ${C}_{4}$ axis, ${\ensuremath{\gamma}}^{e}$ is unenhanced: $\frac{{\ensuremath{\gamma}}_{\ensuremath{\parallel}}^{e}}{2\ensuremath{\pi}}=1.2924\ifmmode\pm\else\textpm\fi{}0.0001$ kHz/G. However, $\frac{{\ensuremath{\gamma}}_{\ensuremath{\perp}}^{e}}{2\ensuremath{\pi}}=2.12\ifmmode\pm\else\textpm\fi{}0.05$ kHz/G shows modest enhancement due to second-order admixture of other $^{1}D_{2}$ electronic levels. This result is used to assign the symmetry of the excited state as ${A}_{1}$ in the point group ${C}_{4v}$, and to locate the $E \mathrm{level}\ensuremath{\sim}200$ ${\mathrm{cm}}^{\ensuremath{-}1}$ higher. Unlike that of the ground state, the excited-state quadrupole coupling is dominated by real electric quadrupole interactions, and the constant is determined to be ${D}^{e}=\ensuremath{-}0.44$ MHz.

Preparation and decay of an excited molecular state studied by optical-rf double resonance

In an optical-radio-frequency double-resonance experiment on NO 2 a broad resonance structure appears superimposed on the normal magnetic resonance spectrum. We show here that the broad resonance structure is associated with the preparation of the free molecule into an initial state and the subsequent, fast (relative to photon emission) evolution into another (long-lived) state from which it decays radiatively. The results confront us with an interesting problem concerning the time evolution of a quantum mechanical system.

Optical hole burning by superhyperfine interactions in CaF_2:Pr^3+

Optical hole burning has been observed in the 5941-A transition of Pr(3+) in a charge-compensated tetragonal site of CaF(2) . The Pr(3+) ground state is doubly degenerate and shows a large first-order hyperfine splitting, which is clearly resolved because of the very narrow inhomogeneous linewidth of 650 MHz. The hole burning involves a new mechanism, in which optically induced spin flips of neighboring nuclei (here (19)F) shift the optical transition frequency outside its homogeneous linewidth. This mechanism was confirmed by optical rf double resonance.

Optically detected nuclear magnetic resonance studies of LiYF4:Pr3+in the ground electronic state3H4

Ground state NMR spectra of Pr3+ in an axial host (LiYF4) have been obtained using an optical RF double resonance experiment in zero and low static magnetic fields. From the data, the authors obtained the spin Hamiltonian constants: gamma x/2 pi = gamma y/2 pi =+8.22+or-0.20 kHz G-1; gamma z/2 pi =+1.924+or-0.005 kHz G-1; D=+4737.2+or-0.2 kHz. The hyperfine interaction constant AJ for the ground state obtained from the measured value of gamma z/2 pi and the available electronic wavefunctions is 1093.8+or-8.8 MHz which is in excellent agreement with Bleaney's results. The dipolar interaction between Pr and F spins gives rise to a zero field structure of the Iz=+or-1/2 to +or-3/2 transition and to extra peaks in the low-field spectrum of the Iz=+or-1/2 to +or-3/2 and Iz=+or-3/2 to +or-u5/2 transitions. Determination of the spin-Hamiltonian constants including the dipolar constants from the observed data is discussed.

Alignment Destroying Cross Sections of the 2p4 State of Neon for Collisions with He3 and He4

Alignment destroying cross sections of the 2p 4 state of neon colliding with He 3 and He 4 atoms are measured by means of optical-rf double resonance of a He-Ne laser. The cross sections measured are (8.88 ±0.33) ×10 -15 cm 2 and (6.89 ±0.37) ×10 -15 cm 2 , respectively. Importance of the short range overlapping force for these collisions is emphasized, rather than the long range van der Waals interaction.

General Higher-Order Effects of Frequency Shifts in Optical-rf Double Resonances

By means of the recursive perturbation method developed by Hioe and Eberly, we present an analytic expression of general fourth-order effects in the frequency shifts of new coherence resonances and multiphoton transitions for the general case that a spin-1/2 atom interacts with an oscillating rf field in optical pumping. Moreover, the validity of the theoretical results is checked by an optical-rf double resonance experiments with cesium vapor, and agreement between observed and calculated results becomes close.

The nuclear quadrupole interaction in Pr 3+:LaF 3 — An optical-RF double resonance measurement of the ground electronic state

The nuclear quadrupole hyperfine splittings of Pr 3+ in LaF 3 have been measured for the ground electronic state using a RF optical resonance technique. A hamiltonian H = P[(I 2 z− 1 3 I(I+1) + (η/6)(I 2 +−I 2 -)] was fitted to the data with z P=4.185 ± 0.003 MHz and η = 0.105 ± 0.010. Linewidths of 180 kHz were observed.

Effect of Transverse Pumping in Optical Pumping

A theoretical and experimental study has been made of the effect of transverse optical pumping in the optical-rf double resonance of cesium atoms. The solution of Bloch type equations shows that the Hanle effect and new type resonances become notable in the weak magnetic field or for strong rf field, as the effect of the transverse pumping. The new type resonances appear in the unmodulated component and the components modulated at the first and the second harmonics of the applied rf frequency in the pumping light beam transmitted through the sample cell. It is predicted that the new type resonances are not only shifted but also broadened as the intensity of rf field increases. The shift, broadening and the intensity for observed new type resonances are in good agreement with the theoretical prediction.

Level Crossing and Double Resonance on the A 1π State of CS

Using the coincident atomic spectral line MnII 2576.1 to pump the R(7) transition of the 0–0 band, level crossing and double resonance are observed in the 1Π state of carbon monosulfide. From the Hanle effect a lifetime value of 2.0 ± 0.4 × 10−7 sec is obtained. The analogous Stark level crossing effect and the Stark–Zeeman recrossing effect give estimates of the dipole moment μ and lambda doubling δ. With an rf search aided by these estimates, optical-rf double resonance provides more accurate values: μ8 = 0.68 ± 0.01 D; δ8 = 1099.4 ± 0.3 MHz for the J = 8 level. Considering the effect of nearby perturbing states, it is estimated that μΠ = μ8 ± 0.08 D. A derivation of signal intensity for the double resonance experiment is used to obtain the rf power requirements and criteria for selecting the optimum polarization.