Preprints
1. An ab initio spectroscopic model of the molecular oxygen atmospheric and infrared bands
2024
The preprint of the following publication can be downloaded from: https://arxiv.org/abs/2504.04214
W. Somogyi et al., Phys.Chem.Chem.Phys, 26, 27419-27430 (2024) DOI: 10.1039/d4cp02619e
2. Reference-free dual-comb spectroscopy with inbuilt coherence
2024
The preprint of the following publication can be downloaded from: https://arxiv.org/abs/2405.03182
M. Roiz, S. Larnimaa, T. Uotila, M. Närhi, and M. Vainio, "Reference-free dual-comb spectroscopy with inbuilt coherence," Opt. Lett. 49, 2473-2476 (2024). https://doi.org/10.1364/OL.521866
3. Leveraging resonant frequencies of an optical cavity for spectroscopic measurement of gas temperature and concentration
2025
UMK published a preprint titled "Leveraging resonant frequencies of an optical cavity for spectroscopic measurement of gas temperature and concentration" to arXiv repository.
In this work, UMK introduced a spectroscopic approach to primary gas thermometry, harnessing precise optical cavity resonance frequencies and ab initio molecular line intensity calculations. By utilizing CO (3-0) vibrational band lines and cavity mode dispersion spectroscopy, we achieve an uncertainty of 82 ppm (24 mK at 296 K) in line-intensity-ratio thermometry (LRT)—over an order of magnitude lower than any previously reported spectroscopic thermometry at gas pressures above 1.2 kPa.
The preprint can be downloaded from arXiv: https://arxiv.org/abs/2502.17660
The work is now published in Physical Review Letter.
4. Measurement of carbon monoxide pressure broadening and temperature dependence coefficients in the 1←0 band
2025
Preprint for PCCP publication: https://oar.ptb.de/resources/show/10.7795/120.20250506
Denghao Zhu, Leopold Seifert, Sumit Agarwal, Bo Shu, Ravi Fernandes and Zhechao Qu. PCCP 2025 (In press) DOI: 10.1039/d5cp00161g
5. Cavity ring-down spectroscopy at 2-µm wavelength assisted by a comb-locked optical parametric oscillator
2025
PriSpecTemp partner at UniCampania led by Antonio Castrillo and Livio Gianfrani developed a high-precision spectrometer for molecular spectroscopy at 2 μm, leveraging a novel comb-locked optical parametric oscillator (OPO) as a reference laser. This system achieves absolute frequency accuracy of 108 kHz—critical for advancing metrology in atmospheric and astrophysical sciences.
Vittorio DAgostino, Eugenio Fasci, Muhammad Khan, Stefania Gravina, Livio Gianfrani, and Antonio Castrillo, Optics Letters, DOI 10.1364/OL.563855
ArXiv link:
https://arxiv.org/abs/2505.23418
6. Metrology for climate action
2025
To accurately understand climate and environmental changes, it's crucial to have precise and reliable measurements, especially in a complex system that includes various physical and chemical parameters. Germany's national metrology institute, the Physikalisch-Technische Bundesanstalt (PTB), has taken initiatives to align its metrology efforts with climate action and environmental protection. The so founded Innovation Cluster Environment & Climate (IC-U) has implemented strategic actions to tackle the metrological challenges related to climate change and environmental threats. From air quality to z-score evaluation, PTB is serving metrology research needs and customer demands with respect to climate and environment topics. This contribution showcases examples spanning from optical gas standards (OGS) for air quality networks, neutron scattering-based soil moisture measurements and radon metrology applied to greenhouse gas transportation, to quantum chemistry applications for remote sensing with uncertainty figures as small as 0.14 %.
Zenodo link:
7. FEM analysis of thermal properties of an optical gas cell for ro-vibrational spectroscopic thermometry
2025
We utilised Finite Element Method (FEM) to analyse the thermal behaviour of newly designed optical gas cell. we have investigated the impact of the gas pressure, design of the optical windows, thermal radiation and the flow regime inside the heat exchanger on the temperature gradient in the spectroscopic gas cells. Considering practical spectroscopic measurement conditions, the simulation covered wide ranges of pressure and temperature, from 1 mbar to 1000 mbar, and from 200 K to 400 K, respectively. The results of the FEM analysis highlight the significance of the design of optical windows, including the size and isolation, in maintaining gas thermodynamic stability and homogeneity. Moreover, the simulation demonstrates how temperature profiles vary in different conditions and how viscous dissipation in the heat exchanger fluid affects the gas temperature uniformity. Furthermore, the study emphasises the importance of the place where the temperature sensor is installed, for accurate temperature measurement. The findings of this research aim to provide valuable insights for the future design of optical gas cells.
Zenodo link:
8. International comparison CCQM-P229 pilot study to measure line intensities of selected 12C16O transition
2025
We present primary spectroscopic measurements of line intensities in the 3-0 vibrational band of 12C16O. This international measurement campaign was organized under the auspices of the Consultative Committee for Amount of Substance (CCQM) and involved six laboratories carrying out independent measurements of more than forty rotation-vibration transitions. A total of three measurement techniques on samples of pure carbon monoxide were applied in this intercomparison, including Fourier transform spectroscopy, cavity ring-down spectroscopy, and cavity mode dispersion spectroscopy. Using advanced spectroscopic line shape models and thorough characterization of instrument response to analyze the measured spectra, artifact-free measurements of line intensities were obtained by each laboratory. Average intensities were weighted by the inverse of the combined variance determined from rigorous estimates of combined systematic and statistical uncertainties. Results for all lines from five of the laboratories were scattered about the weighted mean value by nominally one part per thousand. Comparison of the weighted integrated band intensity with quantum-chemical calculations differed by nominally one part per ten thousand, thus demonstrating excellent agreement between experiment and theory. These results serve as an experimental benchmark for assessing the uncertainty in theoretical calculations, and they reveal the benefits of coordinated experiments that leverage complementary and independent primary measurements from contributing laboratories.
Zenodo link:
9. Cavity ring-down spectroscopy at 2- um wavelength assisted by a comb-locked optical parametric oscillator
2025
We report on a comb-locked cavity ring-down spectrometer developed for high-precision molecular spectroscopy at 2 um. 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 N2O transitions belonging to hot vibrational bands. One of these, never observed before, is included in the N2O line list of the ExoMol database. Absolute center frequencies are retrieved with a 1-sigma global uncertainty of 108 kHz.
ArXiv link: