arXiv subjects

W. Jastrzebski

Publications and source records attributed to W. Jastrzebski.

6 recordsLinked to original sources

arXiv2025

The C$^1Π_{\mathrm{u}}$ state of potassium dimer revisited: an~extensive study by polarisation labelling spectroscopy method

The polarisation labelling spectroscopy technique was applied to study the C$^1Π_{\mathrm{u}}$ $\leftarrow$ X$^1Σ^{+}_{\mathrm{g}}$ band system in potassium dimer. About 1100 new rotationally resolved molecular lines were measured in the $22100-24100$~cm$^{-1}$ spectral range. Perturbations of the lowest vibrational levels of the C state were localised and their origin discussed. A set of Dunham coefficients was deduced to fit the unperturbed levels of the C$^1Π_{\mathrm{u}}$ state with $0 \le v \le 38$ and $18 \le J \le 101$ and the potential energy curve of the state was constructed.

physics.atom-ph↗

arXiv2025

The double minimum E(3)$^1Σ^{+}_{\mathrm{u}}$ state in Cs$_2$

The double minimum E$^1Σ^{+}_{\mathrm{u}}$ state in caesium dimer was investigated by analysing spectra of the E$^1Σ^{+}_{\mathrm{u}}$ $\leftarrow$ X$^1Σ^{+}_{\mathrm{g}}$ band system, simplified by polarisation labelling. A total of 6727 rotationally resolved transitions to levels situated in the inner well and above the internal barrier were identified and a potential energy curve allowing to reproduce their energies was constructed using the Fourier grid Hamiltonian and inverted perturbation approach methods. The unambiguousness of the potential curve in view of lack of data related to levels located in the outer well is discussed.

physics.atom-ph↗

arXiv2009

On the B^1Πstate of NaCs

The B^1Π<- X^1Σ^+ system of NaCs molecule is investigated experimentally by polarization labelling spectroscopy technique. The inverted perturbation approach method is used to construct the potential energy curve of the B^1Πstate, providing accurate eigenenergies for vibrational levels v = 0 - 15.

physics.chem-ph↗

arXiv2004

A regularized inverted perturbation approach method: potential energy curve of the $4^1Σ^+_u$ state in $Na_2$

We describe a modification of the inverted perturbation approach method allowing to construct physically sensible potential energy curves for electronic states of diatomic molecules even when some parts of the potential are not adequately characterized by the experimental data. The method is based on a simple regularization procedure, imposing an additional constraint on the constructed potential curve. In the present work it is applied to the double minimum 4$^1Σ^{+}_{\mathrm u}$ state of Na$_2$, observed experimentally by polarization labeling spectroscopy technique.

physics.atom-ph↗

arXiv2003

Collisional properties of ultracold K-Rb mixtures

We determine the inter-species s-wave triplet scattering length a3 for all K-Rb isotopic mixtures by measuring the cross-section for collisions between 41K and 87Rb in different temperature regimes. The positive value a3=+163(+57,-12)a0 ensures the stability of binary 41K-87Rb Bose-Einstein condensates. For the fermion-boson mixture 40K-87Rb we obtain a large and negative scattering length which implies an efficient sympathetic cooling of the fermionic species down to the degenerate regime.

cond-mat.soft↗

arXiv2000

An Optical Trap for Collisional Studies on Cold Fermionic Potassium

We report on trapping of fermionic 40K atoms in a red-detuned standing-wave optical trap, loaded from a magneto-optical trap. Typically, 10^6 atoms are loaded at a density of 10^12 cm^-3 and a temperature of 65 microK, and trapped for more than 1 s. The optical trap appears to be the proper environment for performing collisional measurements on the cold atomic sample. In particular we measure the elastic collisional rate by detecting the rethermalization following an intentional parametric heating of the atomic sample. We also measure the inelastic two-body collisional rates for unpolarized atoms in the ground hyperfine states, through detection of trap losses.

physics.atom-ph↗