Experimental observation of Doppler-free signals for weak transitions can be greatly facilitated by an estimate for their expected amplitudes. We derive an analytical model which allows the Doppler-free amplitude to be estimated for small Doppler-free signals. Application of this model to formaldehyde allows the amplitude of experimentally observed Doppler-free signals to be reproduced to within the experimental error.
The method of Doppler - free comb - spectroscopy for dipole transitions was proposed. The calculations for susceptibility spectrum for moving two-level atoms driving by strong counter propagating combs have been done. The used theoretical method base
d on the Fourier expansion of the components of density matrix on two rows on kv (v-velocity of group of atoms, k-projection of wave vector) and {Omega} (frequency between comb components). For testing of validity of this method the direct numerical integration was done. The narrow peaks with homogeneous width arise on the background of Doppler counter. The contrast of these peaks is large for largest amplitudes of comb-components. Power broadening is increasing with increase of field amplitudes. The spectral range of absorption spectrum is determined by the spectral range of comb generator and all homogeneous lines arise simultaneously. The spectral resolution is determined by the width of homogeneously-broadening lines. The physical nature of narrow peaks is in the existence of multi-photon transitions between manifolds of quasi-energy levels arising for different groups of atoms moving with velocities that satisfy to the resonant conditions 2kv= (n+l){Omega}, where n, l - are integers and {Omega} - frequency difference between comb teeth.
We demonstrate a simple technique to measure the resonant frequency of the 398.9 nm 1S0 - 1P1 transition for the different Yb isotopes. The technique, that works by observing and aligning fluorescence spots, has enabled us to measure transition frequ
encies and isotope shifts with an accuracy of 60 MHz. We provide wavelength measurements for the transition that differ from previously published work. Our technique also allows for the determination of Doppler shifted transition frequencies for photoionisation experiments when the atomic beam and laser beam are not perpendicular and furthermore allows us to determine the average velocity of the atoms along the direction of atomic beam.
We develop a systematic analytical approach on linear and nonlinear pulse propagations in an open Lambda-type molecular system with Doppler broadening. In linear case, by using residue theorem and a spectrum decomposition method, we prove that there
exists a crossover from electromagnetically induced transparency (EIT) to Autler-Townes splitting (ATS) for co-propagating configuration of probe and control fields. However, there is no EIT and hence no EIT-ATS crossover for counter-propagating configuration. We give various explicit formulas, including probe-field spectrum decomposition, EIT condition, width of EIT transparency window, as well as a comparison with the result of cold molecules. Our analytical result agrees well with the experimental one reported recently by A. Lazoudis et al. [Phys. Rev.A82, 023812 (2010)]. In nonlinear case, by using the method of multiple-scales, we derive a nonlinear envelope equation for probe-field propagation. We show that stable ultraslow solitons can be realized in the open molecular system.
The $3p^{4}$ $^{3}$P$_{J}$ - $3p^{3}4p$ $^{3}$P$_{J}$ transition in the sulphur atom is investigated in a precision two-photon excitation scheme under Doppler-free and collision-free circumstances yielding an absolute accuracy of 0.0009 cm$^{-1}$, us
ing a narrowband pulsed laser. This verifies and improves the level separations between amply studied odd parity levels with even parity levels in S I. An improved value for the $^{3}$P$_{2}$ - $^{3}$P$_{1}$ ground state fine structure splitting is determined at $396.0564$ (7) cm$^{-1}$. A $^{34}$S - $^{32}$S atomic isotope shift was measured from combining time-of-flight mass spectrometry with laser spectroscopy.
A contribution is presented to the study of hadron spectroscopy through the use of fractals and discrete scale invariance implying log-periodic corrections to continuous scaling. The masses of mesons and baryons, reported by the Particle Data Group (
PDG), are properly fitted with help of the equation derived from the discrete-scale invariance (DSI) model. The same property is observed for the mass ratios between different particle species. This is also the case for total widths of several hadronic species. Each fitted parameter, as a function of the hadronic masses, displays the same distribution for all hadronic species. Several masses of still unobserved mesons and baryons are tentatively predicted.
M. Zeppenfeld
,M. Motsch
,P.W.H. Pinkse
.
(2007)
.
"Doppler-Free Spectroscopy of Weak Transitions: An Analytical Model Applied to Formaldehyde"
.
P. W. H. Pinkse
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