Doppler-free Two-photon Transitions Research Articles

Doppler-free two-photon spectroscopy of the 2ν3 band of SF6

High-resolution spectroscopy of the 2ν3 band of SF6 is reported by means of Doppler-free two-photon transitions. Parts of spectra are measured with accuracy of 10−9. This technique applied to SF6 should lead to an assignment of the spectra involved.

Flashlamp pumped tunable dye laser of ultra-narrow bandwidth

A flash lamp pumped dye laser with a ring cavity is injected with the light beam coming from a stabilized singlemode c.w. dye laser. The light emitted by the pulsed laser is analysed either by a Fabry Perot etalon, or by producing a Doppler-free two-photon transition. The bandwidth of the pulsed laser is identical to the one of the c.w. laser; but the pulsed light is shifted to higher frequency by an amount of a few MHz.

Doppler-free two-photon optogalvanic spectroscopy

We describe the use of a new Doppler-free technique, two-photon optogalvanic spectroscopy (TOGS) in the observation of thirteen transitions from the four levels in the 3s configuration of 20Ne. The transitions from the two nonmetastable 3s levels are the first Doppler-free two-photon transitions reported from energy levels other than ground or metastable levels. This is also the first report of Doppler-free measurement of the 4d[5/2] J = 2–4d[5/2] J = 3 splitting in 20Ne.

Doppler-free two-photon transitions to Rydberg levels: convenient, useful, and precise reference wavelengths for dye lasers

We used a tunable cw dye laser to observe Doppler-free two-photon transitions to alkali-atom Rydberg levels. Real-time signals were obtained in an ionization cell of appropriate construction. The two-photon transition wavelengths to rubidium s levels were measured up to n = 50 with better than 1 x 10(-7) absolute accuracy and can be represented to within the experimental precision by a simple function of the principal quantum number, Other related transitions and future possibilities are considered.

Doppler-free two-photon laser spectroscopy of lithium

The hyperfine splitting of the excited 4s 2S1/2 state of the stable Li isotopes 6Li and 7Li was resolved in Doppler-free two-photon transitions from the 2s 2S1/2 ground state. The isotopic shift of the 2s–4s transition was measured, yielding Δν6–7 = 13.72(3) GHz.

Isotopic shift, pressure shift, and pressure broadening of the7d′states of neon using Doppler-free two-photon absorption spectroscopy

Doppler-free two-photon transitions between the $3s$, $J=2$ metastable state and the subconfiguration $7{d}^{\ensuremath{'}}$ of neon are studied with a pulsed-dye-laser oscillator-amplifier system which was synchronized with a chopped rf discharge in neon vapor. The isotopic shifts for these transitions are measured, and based on these measurements we have made a systematic study of Ne-Ne and Ne-He collisional broadening and shift of these very narrow Doppler-free two-photon resonances.

Doppler-free two-photon transitions of the sodium molecule

We report here new Doppler-free two-photon transitions found in high-density sodium vapor. The transitions are due to Na 2 molecules; one of the excited levels involved belongs to a hitherto to unknown 1Σ + g state of Na 2.

Isotropic and quadrupolar components of doppler-free two-photon transition in Ne

The experimental recording of the hyperfine components of the 1s 5 ( J=2) → 4 s ‴'1( J=2) Doppler free two-photon transition in 12Ne shows that the transition operator is the sum of two tensors of rank 0 and 2. We compare the experimental ratio between the isotropic and quadrupolar spectra with a theoretical calculation.

Two-photon spectroscopy. II. Effects of residual Doppler broadening

For pt.I see ibid., vol.8, p.1795 (1975) where the theory of Doppler-free two-photon transitions was discussed for the case of one single laser frequency. Here, the effects of two different frequencies are considered. When the residual Doppler width of the two-photon transition is less than the natural linewidth, the previous results are essentially regained. For large residual Doppler shifts, the absorption profile is a power-broadened Lorentzian if the frequency of the probe field is larger than the frequency of the strong field. In the opposite case, the absorption peak splits because of the AC Stark effect. The high-intensity distortions are minimized when equal frequencies can be used. Power-dependent shifts do not ordinarily occur with a resonantly tuned intermediate level. Some modifications of the spectra are introduced by phase-disturbing collisions.

Doppler-free resonant two-photon transition for isotope separation

The Doppler-free two-photon transition by the use of two opposing laser beams makes the highly selective excitation of isotopic molecules possible. Saturation and pressure dependence of Doppler-free two-photon excitation with arbitrary amplitudes of the optical fields have been calculated and compared with those of the two-step transition and the single-photon transition. The result at the Doppler limit for low pressure gas reveals that the probability of the selective two-photon excitation with a moderate laser power can be larger than that of the single-photon excitation as well as that of the two-step excitation.

Doppler-free two-photon spectroscopy of neon

Doppler-free two-photon transition between the $3s$, $J=2$ metastable state and the $4{d}^{\ensuremath{'}}(\frac{5}{2})$, $J=3$ excited state of neon has been performed with a monomode cw dye laser. We have measured the hyperfine constants of the $4{d}^{\ensuremath{'}}(\frac{5}{2})$, $J=3$ state of $^{21}\mathrm{Ne}$ to be $A=\ensuremath{-}235.9\ifmmode\pm\else\textpm\fi{}0.6$ MHz and $B=11\ifmmode\pm\else\textpm\fi{}9$ MHz. The isotopic shifts for this two-photon transition are $E(^{22}\mathrm{Ne})\ensuremath{-}E(^{20}\mathrm{Ne})=2780.0\ifmmode\pm\else\textpm\fi{}2.5$ MHz and $E(^{21}\mathrm{Ne})\ensuremath{-}E(^{20}\mathrm{Ne})=1452\ifmmode\pm\else\textpm\fi{}6$ MHz. From these results, the possibility of a slight departure from the mass formula cannot be rejected.

Two-photon spectroscopy: effects of a resonant intermediate state

Discusses the theory of Doppler-free two-photon transitions. The theory is worked out for the case of one arbitrarily strong field and one weak field. The Doppler limit is assumed. These simplifications allow the authors to discuss the experimental manifestations of various parameters. They consider power shifts and broadening the number of resonant peaks and their positions. The general case of an off-resonant intermediate state and the single-frequency case with a resonant intermediate state are discussed. The former is found to lead to a power shift, whereas the latter is unshifted in a certain region. In addition the resonant case gives an enhancement without an appreciable increase in width.