arXiv subjects

Stefania Gravina

Publications and source records attributed to Stefania Gravina.

5 recordsLinked to original sources

arXiv2026

Comb-locked cavity ring-down spectroscopy of CO2 at 2-micron wavelength

We report on a comb-locked cavity ring-down spectrometer developed for high-precision, SI-traceable, molecular spectroscopy of air-broadened CO2 gas samples. The experimental setup relies on the use of a singly-resonant optical parametric oscillator that acts as an intermediate link between a 2 micron external-cavity diode laser and an optical frequency comb stabilized against a GPS-disciplined Rb-clock. Absorption spectra of the R(50) ro-vibrational component of the CO2 20012-00001 band have been recorded with high precision and fidelity. As a result of a refined spectral analysis, based on the implementation of the modified Hartmann-Tran profile, line center frequencies, pressure broadening and pressure shifting coefficients have been determined. Finally, we demonstrate the measurement of CO2 mole fractions with a subpromille statistical uncertainty

physics.optics↗

arXiv2025

Isotope shift spectroscopy in mercury vapors: a valid alternative to ytterbium for new physics search

Precision isotope shift metrology in the deep-UV region has been performed for all bosonic isotopes of mercury with a zero nuclear spin, by using the technique of frequency-comb referenced, wavelength-modulated, saturated absorption spectroscopy. The absolute center frequencies of the 6s$^2$ $^1$S$_0$ $\rightarrow$ 6s6p $^3$P$_1$ intercombination line have been measured with precision in the range of 2.5 - 5.9 10$^{-12}$, in temperature-stabilized mercury vapor samples with natural abundances. Frequency shifts in four isotope pairs have been determined with unprecedented accuracy, the global uncertainty being improved by a factor greater than 20 with respect to the best experimental data of the past literature. Our data set, when combined with previous measurements on the 6s6p $^3$P$_2$$\rightarrow$6s7s $^3$S$_1$ transition at 546 nm, allows us to build a King plot that reveals a nonlinearity with a statistical significance of 4.6$\sigma$.

physics.atom-ph↗

arXiv2025

Cavity ringdown spectroscopy at 2 ${\mu}$m wavelength assisted by a comb-locked optical parametric oscillator

We report on a comb-locked cavity ring-down spectrometer developed for high-precision molecular spectroscopy at 2 ${\mu}$m. It is based on the use of an external-cavity diode laser that is offset-frequency locked to the signal output of a singly-resonant optical parametric oscillator. This latter acts as reference laser, being locked to a self-referenced optical frequency comb, which in turn is stabilized against a GPS-disciplined Rb-clock. The performance of the spectrometer is investigated by probing a pair of N$_2$O transitions belonging to hot vibrational bands. One of these, never observed before, is included in the N$_2$O line list of the ExoMol database. Absolute center frequencies are retrieved with a 1-${\sigma}$ global uncertainty of 108 kHz.

physics.optics↗

arXiv2024

Comb-referenced Doppler-free spectrometry of the $^{200}$Hg and $^{202}$Hg intercombination line at 254 nm

We report on precision spectroscopy of the 6s$^2$ $^1$S$_0\to$6s6p $^3$P$_1$ intercombination line of mercury in the deep ultraviolet, by means of a frequency-comb referenced, wavelength-modulated, saturated absorption technique. This method allowed us to perform sub-Doppler investigations with an absolute frequency axis at 254 nm, while ensuring a relatively high signal-to-noise ratio. The absolute line center frequencies of the $^{200}$Hg and $^{202}$Hg bosonic isotopes were measured with a global uncertainty of 8 and 15 kHz (namely, 6.8$\times$10$^{-12}$ and 1.3$\times$10$^{-11}$, in relative terms), respectively, the statistical and systematic components being significantly reduced as compared to past determinations. This remarkable result was achieved also thanks to an in-depth study of the AC stark effect. Furthermore, we found the most accurate $^{200}$Hg-$^{202}$Hg isotope shift ever obtained before, namely, $5295570\pm15_{stat}\pm8_{syst}$ kHz.

physics.atom-ph↗

arXiv2019

Constraining Scalar-Tensor gravity models by S2 star orbits around the Galactic Center

The aim of our investigation is to derive a particular theory among the class of scalar-tensor(ST) theories of gravity, and then to test it by studying kinematics and dynamics of S-stars around supermassive black hole (BH) at Galactic Center (GC). We also discuss the Newtonian limit of this class of ST theories of gravity, as well as its parameters. We compare the observed orbit of S2 star with our simulated orbit which we obtained theoretically with the derived ST potential and constrained the parameters. Using the obtained best fit parameters we calculated orbital precession of S2 star in ST gravity,and found that it has the same direction as in General Relativity (GR), but causes much larger pericenter shift.

astro-ph.GA↗