arXiv subjects

Petr Dohnal

Publications and source records attributed to Petr Dohnal.

5 recordsLinked to original sources

arXiv2025

High Resolution Overtone Spectroscopy of HNC$^+$ and HCN$^+$

Rotationally resolved spectra of the HNC$^+$ and HCN$^+$ molecular ions have been recorded in the spectral range between 6200 and 6800 \rcm\ using a cryogenic ion trap instrument. The rovibrational transitions were probed using two different action spectroscopy schemes, namely laser-induced reaction (LIR) and leak-out spectroscopy (LOS). Various vibrational bands of HNC$^+$ and HCN$^+$ were measured with high resolution for the first time. For HNC$^+$, the $\text{X}~^2\Sigma^+~(20^00)-(00^00)$ overtone band was recorded using LIR, while LOS was used to probe the $\text{X}~^2\Pi~(000)^1-(210)^0\mu$ combination band and the $\text{X}~^2\Pi~(000)^1-\text{A}~^2\Sigma^+~(10^00)$ vibronic band of HCN$^+$. Spectroscopic constants, band origins and radiative lifetimes for the observed states have been determined. The effective fit for the HCN$^+$ spectra revealed the presence of strong vibrational couplings leading to perturbations of the rovibrational levels of the excited states. The two action spectroscopy schemes are compared and their potential use to explore ion-molecule interactions is discussed.

astro-ph.SR↗

arXiv2025

Verification and experimental validation of neutral atom beam source produced by L-PBF

We report validation tests of a calcium atomic-beam source fabricated via Laser Powder Bed Fusion (L-PBF). The surface quality and elemental composition of the printed component were quantitatively assessed, allowing us to establish reference parameters for reliable operation in an ultra-high-vacuum environment. Safe operating conditions of the atomic oven were determined through a combination of simulations and experimental measurements. The ability of the device to deliver an atomic beam to the main experimental region -- the electron/ion trap -- was verified using atomic fluorescence imaging. Fluorescence spectroscopy was further employed to characterize the beam divergence, yielding an emission-cone half-angle of approximately 19 degrees for atoms near the beam axis. A current of atoms on the order of $10^8$ s$^{-1}$ was estimated in the electron-trapping region, which is more than sufficient for anticipated electron-trapping and ion-trapping experiments.

physics.atom-ph↗

arXiv2025

Rovibrational Overtone and Combination Bands of the HCNH+ Ion

Spectra of vibrational overtone and combination bands from vibrational ground state of HCNH+ were measured using an action spectroscopy technique with active background suppression in a cryogenic 22 pole radio frequency ion trap apparatus. Spectroscopic constants for the upper vibrational levels of the transitions were determined with vibrational band origins being 6846.77981(90) $\text{cm}^{-1}$ ($2\nu_1$ , NH stretch), 6640.47624(43) $\text{cm}^{-1}$ ($\nu_1 + \nu_2$), 6282.03578(63) $\text{cm}^{-1}$ ($2\nu_2$, CH stretch), and 6588.4894(20) $\text{cm}^{-1}$ ($\nu_2 + \nu_3 + 2\nu_5^0$). State of the art ab initio VCI calculations up to 10000 $\text{cm}^{-1}$ complement the experimental data.

astro-ph.GA↗

arXiv2024

Overtone Transition $2\nu_1$ of $\text{HCO}^+$ and $\text{HOC}^+$: Origin, Radiative Lifetime, Collisional Quenching

We present spectra of the first overtone vibration transition of $\text{C-H}$/$\text{O-H}$ stretch ($2\nu_1$) in $\text{HCO}^+$ and $\text{HOC}^+$, recorded using a laser induced reaction action scheme inside a cryogenic 22 pole radio frequency trap. Band origins have been located at 6078.68411(19) and 6360.17630(26) $\text{cm}^{-1}$, respectively. We introduce a technique based on mass selective ejection from the ion trap for recording background free action spectra. Varying the number density of the neutral action scheme reactant ($\text{CO}_2$ and Ar, respectively) and collisional partner reactant inside the ion trap, permitted us to estimate the radiative lifetime of the state to be 1.53(34) and 1.22(34) ms, respectively, and the collisional quenching rates of $\text{HCO}^+$ ($2\nu_1$) with He, H$_2$, and N$_2$.

physics.atom-ph↗

arXiv2023

Measurements of rate coefficients of CN$^+$, HCN$^+$ and HNC$^+$ collisions with H$_2$ at cryogenic temperatures

The experimental determination of the reaction rate coefficients for production and destruction of $\text{HCN}^+$ and $\text{HNC}^+$ in collisions with $\text{H}_2$ is presented. A variable temperature 22 pole radio frequency ion trap was used to study the reactions in the temperature range of $17 - 250\;\text{K}$. The obtained rate coefficients for the reaction of $\text{CN}^+$ and of $\text{HCN}^+$ with $\text{H}_2$ are close to the collisional (Langevin) value, whereas that for the reaction of $\text{HNC}^+$ with $\text{H}_2$ is quickly decreasing with increasing temperature. The product branching ratios for the reaction of $\text{CN}^+$ with $\text{H}_2$ are also reported and show a notable decrease of $\text{HNC}^+$ product with respect to $\text{HCN}^+$ product with increasing temperature. These measurements have consequences for current astrochemical models of cyanide chemistry, in particular for the $\text{HCNH}^+$ cation.

astro-ph.GA↗