A. Cygan

Cavity ring-down spectroscopy of the oxygen B-band with absolute frequency reference to the optical frequency comb

Absolute positions of several oxygen B-band lines were measured with the Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectrometer. The frequency axis of spectra was linked to the optical frequency comb. Achieved uncertainties of line positions are between 0.9 and 2.9 MHz. Self-pressure shifts coefficients are also reported.

Active control of the Pound-Drever-Hall error signal offset in high-repetition-rate cavity ring-down spectroscopy

A new approach to realizing the Pound–Drever–Hall (PDH) error signal offset correction is presented. The proposed setup and correction procedure allow one to control not only the effect of amplitude modulation of the error signal, but also other sources of offsets that are present in the PDH feedback loop. This technique significantly improves laser frequency locking in high-repetition-rate cavity ring-down spectroscopy (CRDS) by allowing one to recover a tight PDH lock within 1 ms after switching off the probe laser beam. We apply the PDH error signal offset correction to CRDS measurements of the weak 16O2 B-band R7 Q8 line. The resulting spectra taken at a pressure of 1.2 kPa had a signal-to-noise ratio of ~8000:1.

CRDS investigation of line shapes and intensities of the oxygen B‐band transitions at low pressures

We performed high resolution line shape and line intensity measurements of self‐broadened O2u2009b1Σg+(νu2009=u20091)←Χ3Σg−(νu2009=u20090) band transitions using the frequency‐stabilized cavity ring‐down spectroscopy technique under relatively low‐pressure conditions. We compared our measured line intensities, which had relative uncertainties below 0.7%, to available data.

Spectral line shape problem in the spectroscopic determination of the Boltzmann constant

Simulations of the influence of line shape model on the systematical error in spectroscopic determination of the Doppler width was made on example of the oxygen transition from the visible region of spectrum (λu2009=u2009687u2009nm). Application to optical method of the Boltzmann constant determination was discussed.

Line Shape Study of the 326.1 nm 113Cd line perturbed by Ar and Xe

We report results of measurements of the shapes of two hyperfine‐structure components (F’u2009=u20091/2‐F”u2009=u20091/2 and Fu2009=u20093/2‐F”u2009=u20091/2) of the intercombination 326,1 nm line corresponding to the 51S0‐53P1 transition for the 113Cd isotope perturbed by Xe and Ar. Experiments were performed using a laser‐induced fluorescence method and the values of the pressure broadening, shift and asymmetry coefficients were determined. In the course of the present study we employed a recently verified isotope structure of the 326.1 nm line [1]. Both for 113Cd‐Xe (the emitter to perturber mass ratio 1.15) and 113Cd‐Ar (the mass ratio 0.35) the effects due to correlation between pressure and Doppler broadening of the 326.1 nm line were observed.

Isotope Structure and Hyperfine Splitting of 326.1 nm 113Cd line

In the course of this work the influence of the isotope structure of the 326.1 nm (51S0‐53P1) cadmium line on the resulting line shape was carefully studied. Measurements for the 113Cd line perturbed by Ne at low pressure (below 2 Torr) were used for determination of isotope shifts of cadmium hyperfine components. The results has been used as a starting point for the analysis of more than 90 spectra of the line under investigation perturbed by different gasses in wide pressure range. That allowed us to determine the hyperfine splitting for 113Cd 326.1 nm line with uncertainty below 10−3 cm−1.