The development of increasingly sensitive and robust instruments and new methodologies are essential to improve our understanding of the Earth’s climate and air pollution. In this context, Dual-Comb ...spectroscopy (DCS) has been successfully demonstrated as a remote laser-based instrument to probe infrared absorbing species such as greenhouse gases. We present here a study of the sensitivity of Dual-Comb spectroscopy to remotely monitor atmospheric gases focusing on molecules that absorb in the ultraviolet domain, where the most reactive molecules of the atmosphere (OH, HONO, BrO...) have their highest absorption cross-sections. We assess the achievable signal-to-noise ratio (SNR) and the corresponding minimum absorption sensitivity of DCS in the ultraviolet range. We propose a potential light source for remote sensing UV-DCS and discuss the degree of immunity of UV-DCS to atmospheric turbulences. We show that the characteristics of the currently available UV sources are compatible with the unambiguous identification of UV absorbing gases by UV-DCS.
We show that our developed free-running, bidirectional ring Ti:Sa laser cavity meets the requirements for Dual Comb Spectroscopy in the UV range (UV-DCS). Two counter-propagative frequency combs with ...slightly different repetition rate are generated in such a cavity and we show quantitatively that this repetition rate difference can be explained by the self-steepening effect. Molecular absorption lines of the O2
A
-band centered around 760~nm are measured with a 1,5 GHz spectral resolution, demonstrating that the mutual coherence of the two combs allows GHz-resolution DCS measurements. Moreover, we demonstrate that the generated output peak power allows for efficient second harmonic generation (SHG), in the scope of developing laboratory and open-path UV-DCS experiments.
We present a new measurement of the 1S-3S two-photon transition frequency of hydrogen, realized with a continuous-wave excitation laser at 205 nm on a room-temperature atomic beam, with a relative ...uncertainty of 9×10^{-13}. The proton charge radius deduced from this measurement, r_{p}=0.877(13) fm, is in very good agreement with the current CODATA-recommended value. This result contributes to the ongoing search to solve the proton charge radius puzzle, which arose from a discrepancy between the CODATA value and a more precise determination of r_{p} from muonic hydrogen spectroscopy.
We report the first measurement of resolved molecular absorption lines with dual-comb spectroscopy using a Kerr-lens mode-locked bidirectional Ti:sapphire ring laser cavity. A 3 nm broad spectrum has ...been recorded in 5.3 ms with a spectral resolution of ≈ 1 GHz (0.05 cm-1) corresponding to a relative spectral resolution of 2.5 × 10
−6
. The measurement of spectrally resolved molecular absorption lines have been demonstrated on the oxygen
A
-band at 394 THz (760 nm, 13 000 cm
−1
) and was obtained with two free-running 100 fs Ti:sapphire trains of pulses without the need for active phase stabilization protocol nor real-time or post-processing correction. This work demonstrates that the bidirectional laser configuration enables a sufficient level of absolute and mutual coherence for dual-comb spectroscopy of resolved molecular absorption lines. Considering the high versatility of Ti:sapphire emission spectral range (from 600 to 1100 nm) with high-peak powers, the here reported results pave the way for Dual-Comb spectroscopy in the UV range at mW average output power using a standalone set-up, in the aim to extend its applicability for atmospheric remote-sensing.
Monitoring the emission of gases is difficult to achieve in industrial sites and in environments presenting poor infrastructures. Hence, robust methodologies should be developed and coupled to Lidar ...technology to allow remote sensing of gas emission. OSAS is a new methodology to evaluate gas concentration emission from spectrally integrated differential absorption measurements. Proof of concept of OSAS-Lidar for CH
4
emission monitoring is here presented.
The energy levels of hydrogen-like atomic systems can be calculated with great precision. Starting from their quantum mechanical solution, they have been refined over the years to include the ...electron spin, the relativistic and quantum field effects, and tiny energy shifts related to the complex structure of the nucleus. These energy shifts caused by the nuclear structure are vastly magnified in hydrogen-like systems formed by a negative muon and a nucleus, so spectroscopy of these muonic ions can be used to investigate the nuclear structure with high precision. Here we present the measurement of two 2S-2P transitions in the muonic helium-4 ion that yields a precise determination of the root-mean-square charge radius of the α particle of 1.67824(83) femtometres. This determination from atomic spectroscopy is in excellent agreement with the value from electron scattering
, but a factor of 4.8 more precise, providing a benchmark for few-nucleon theories, lattice quantum chromodynamics and electron scattering. This agreement also constrains several beyond-standard-model theories proposed to explain the proton-radius puzzle
, in line with recent determinations of the proton charge radius
, and establishes spectroscopy of light muonic atoms and ions as a precise tool for studies of nuclear properties.
High resolution spectroscopy of the hydrogen atom takes on particular importance in the new SI, as it allows to accurately determine fundamental constants, such as the Rydberg constant and the proton ...charge radius. Recently, the second most precisely measured transition frequency in hydrogen, 1S−3S, is obtained by our group. In the context of the Proton Radius Puzzle, this result calls for further investigation.
High resolution spectroscopy of the 1S–3S transition of the hydrogen atom at 300 K has been achieved at LKB, Paris, with an uncertainty of 9e‐13. The deduced value of the proton radius is in good agreement with the latest Codata adjustment. It however disagrees with the value from muonic hydrogen spectroscopy, as with other recent results.
This paper reports on the generation of 15 mW of continuous narrow-band laser source at 205 nm. The infra-red light source provided by a Titanium-Sapphire (TiSa) laser is mixed with the fourth ...harmonic of a Nd:YVO sub(4) laser by the use of a beta -barium borate (BBO) non-linear crystal. This highly reliable and powerful ultraviolet (UV) source is an ideal tool for the 1S-3S hydrogen spectroscopy. Moreover, the wide tunability of the TiSa laser combined with this experimental set up makes the generation of bright deep ultra-violet (D-UV) sources possible. In particular, we plan to produce a 194 nm continuous light beam which is necessary to perform the 1S-4S transition in hydrogen.
This paper reports on the generation of 15mW of continuous narrow-band laser source at 205nm. The infra-red light source provided by a Titanium-Sapphire (TiSa) laser is mixed with the fourth harmonic ...of a Nd:YVO4 laser by the use of a β-barium borate (BBO) non-linear crystal. This highly reliable and powerful ultraviolet (UV) source is an ideal tool for the 1S–3S hydrogen spectroscopy. Moreover, the wide tunability of the TiSa laser combined with this experimental set up makes the generation of bright deep ultra-violet (D-UV) sources possible. In particular, we plan to produce a 194nm continuous light beam which is necessary to perform the 1S–4S transition in hydrogen.
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