Luận án ứng dụng laser trong quang phổ phân tích phân tử đa nguyên tử

UNIVERSITÉ PARIS 13 - SORBONNE PARIS CITÉ LABORATOIRE DE PHYSIQUE DES LASERS Thèse de doctorat pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ PARIS 13 Discipline : PHYSIQUE présentée et soutenue publiquement par Dang Bao An Tran Widely tunable and SI-traceable frequency-comb-stabilised mid-infrared quantum cascade laser : application to high precision spectroscopic measurements of polyatomic molecules Soutenue le 15 Juillet 2019 devant le jury composé de : Prof. Anne Amy-Klein LPL Directrice de thèse Dr. Alain Campargue LIPHY Président Dr. Caroline Champenois PIIM Rapporteuse Dr.

Benoît Darquié LPL Co-encadrant Prof. Laurent Hilico LKB Rapporteur Dr. Rodolphe Le Targat LNE-SYRTE Examinateur Prof. Gaël Mouret LPCA Examinateur Dr.

Gabriele Santambrogio LENS Examinateur L’équipe Métrologie, Molécules et Tests Fondamentaux (MMTF) Laboratoire de Physique des Lasers Université Paris 13, CNRS - UMR 7538 99 Avenue Jean Baptiste Clément, 93430 Villetaneuse, France Acknowledgement My work has been performed at the Metrology, Molecules, and Fundamental Tests (MMTF) group, Laboratoire de Physique des Lasers (LPL), CNRS, Université Paris 13. First of all, I am deeply grateful to my supervisors Prof. Anne Amy-Klein and Dr. To Anne, thank you both for your guidance and encouragement during four years of work.

To Benoît, thank you all for your support, and boundless patience. I wouldn’t got anything done without your continuous presence in laboratory. I am proud to have studied under the two of you. On top of that, I gratefully acknowledge this opportunity to work with you.

I would like to thank Prof. Laurent Hilico and Dr. Caroline Champenois for reviewing my thesis. I also thank other members of my board of examiners, Dr.

Alain Campargue, Prof. Gaël Mouret, Dr. Rodolphe Le Targat, and Dr. I would also like to thank Dr.

Olivier Lopez for continual support for electronic control. The experience and the knowledge I got from him is invaluable and will help my further teaching greatly at HCMC University of Education, Vietnam. Sean Tokunaga, thanks for your support for programming and optical alignment. A special thanks to Dr.

Rosa Santagata with whom we tried to develop the experiment together. Many of the results presented in this thesis resulted from working with her. Anne Cournol and Dr. Mathieu Manceau, thank you for all your advice about the experiment, also to Matthieu Pierens and Louis Lecordier for interesting discussions.

From Paris, I would like to thank Dr. Thomas Wall for the precious opportunity to understand the experimental setups at the Centre for Cold Matter, Imperial College London. To researchers at LNE-SYRTE, thank you a lot for the best reference signal. I wouldn’t have finished my work without the collaboration between LPL and LNE- SYRTE.

I would also like to thank all the members of the MMTF group. Frédéric Du Burck, Dr. Vincent Roncin, Amine Chaouche Ramdane, Karim Mana- manni, thanks all for your discussions and working together in the same laboratory in the first three years. Christophe Daussy and Dr.

Moufarej Elias, thanks for sharing optical components, and to the other members for your valuable support. Ha Tran, Laboratoire de Météorologie Dynamique, Sorbonne Université and Dr. Ba-Tong Nguyen, Laboratoire de Physico-Chimie de l’Atmosphére, Université du Littoral Côte d’Opale, thank you all for discussions about molecular spectroscopy. I would also like to thank to Olivier Gorceix, former director of LPL, for welcoming me in such a great working environment.

I also thank all supports from administrative group: Carole Grangier, Maryse Médina, Sylvie Spielmann, and Solen Guezennec, from the mechanics workshop: Albert Kaladjian and his colleagues, from the electronic workshop: Fabrice Wiotte and his colleagues, from the optics workshop: Thierry Billeton, and from IT technicians: Marc Barbier and Stéphane Simonazzi. I gratefully acknowledge the Ministry of Education and Training, Vietnam (Program 911) for financial support during four years and L’école Doctorale Sciences, Technologies Santé - Galilée, Université Paris 13 for additional financial support. I would also like thank to my colleagues at Faculty of Physics, HCMC University of Education, Vietnam who have shared the teaching work during this course. Finally, I would like to thank my family in Vietnam and my Vietnamese friends in France, especially, family of Dr.

Van-Tuan Nguyen, a postdoc at Institut Pasteur, Paris and Thanh-Tuan Nguyen, a PhD student at Université de Toulon. iv Contents Acknowledgement iii Introduction 1 1 Spectroscopic studies with molecules: principle and applications 5 1.2 Linear absorption spectroscopy .3 Saturated absorption spectroscopy .2 Tools for frequency control, high resolution spectroscopy, and metrology .2 Ultra-stable signal .3 The optical frequency comb .4 Optical frequency dissemination .3 Mid-infrared laser stabilization .1 The need for mid-infared laser stabilization .2 Methods for the frequency stabilization of mid-infrared lasers .4 Previous precise molecular spectroscopic measurement at LPL .5 Parity violation observation .1 Parity violation in chiral molecules .2 Proposed experimental approaches of the parity violation observa- tion in chiral molecules .3 Searching new chiral molecules .4 New experimental setup under development. 33 2 Tunable and SI-traceable optical frequency comb stabilized to a remote optical frequency reference signal 35 2.2 Reference signals from LNE-SYRTE .1 Primary microwave reference signal .2 Ultra-stable near-IR frequency reference from LNE-SYRTE .3 Calibration of the US laser frequency to the primary standards .3 Transfer of a stabilized frequency reference between LNE-SYRTE and LPL 44 2.1 Principle of fiber based optical frequency transfer .2 Optical frequency transfer between LNE-SYRTE and LPL .4 Local radio frequency references .5 Widely tunable and ultra-stable optical local oscillator at 1.2 Low-phase noise microwave synthesizer without phase jumps .6 The optical frequency comb at LPL .1 The OFC at LPL: introduction and modules .2 Free-running optical frequency comb .7 Frequency stabilization of the OFC repetition rate onto the OLO .2 Performances of the stabilization of the repetition rate of the OFC 65 2.3 Upgrading the experimental setup .8 OFC repetition rate tuning performances. 71 3 Development of a quantum cascade laser based widely tunable ultra- high resolution spectrometer 73 3.2 Quantum cascade laser .1 What is a quantum cascade laser? .2 The LPL mid-infrared quantum cascade laser .3 Frequency stabilization of a quantum cascade laser to an optical frequency comb .1 Sum frequency generation .2 Locking the quantum cascade laser to the optical frequency comb .3 Performances of the QCL frequency stabilization .4 The QCL frequency control: summary and SI-traceability .2 SI-traceability of the QCL frequency .3 Determination of the QCL absolute frequency .5 Quantum cascade laser frequency tuning .1 Wide frequency tuning of the stabilized QCL using the step motor 105 3.2 Using neighbouring modes .3 Using a radio-frequency-stabilized OFC.

109 4 High-precision mid-infrared spectrometer: application to the spectroscopy of methanol 111 4.1 The high-precision widely tunable SI-tracable QCL-based mid-infrared spectrometer .3 Frequency modulation setup for saturated absorption spectroscopy 116 4.2 Rovibrational spectrum of methanol: an overview .1 Methanol: a molecule with a variety of interests .2 Structure of rovibrational energy levels and notation .4 High resolution spectroscopy of methanol in the literature .3 Doppler-limited spectroscopy .2 Data processing and results .4 Precise spectroscopy of methanol .2 Analysis of experimental data .1 Power-induced frequency shift .2 Pressure-induced frequency shift .3 Power- and pressure-induced broadening effects .4 Estimation of the transition dipole moment .6 Absolute frequency measurement of rovibrational transitions of methanol 142 4.1 Absolute frequency measurement of the P(E,co,0,2,33) methanol transition .2 Absolute frequency determination of other methanol transitions .7 Asymmetry K -doublets for A-symmetry transitions .2 Un-resolved K-doublet .8 Tunability and spectral coverage. 176 5 High-resolution spectroscopy of trioxane and ammonia 179 5.2 High-precision spectroscopy of trioxane .2 Direct absorption spectrum of the ν5 vibrational mode of trioxane 182 5.3 Saturated absorption spectroscopy in the ν5 vibrational mode of trioxane .4 Broadband saturated absorption spectra of trioxane .5 Spectroscopic constants of trioxane .3 Hyperfine structure in ammonia .2 The hyperfine structure in ammonia .3 Saturated absorption spectroscopy of the ν2 vibrational mode asR(1,1) ammonia transition .4 Hyperfine structure analysis and spectroscopic parameters. 207 General conclusion and perspectives 208 A K+K counter 213 B Technical protocol for the sum frequency generation process 215 B.1 Creating a free space SFG signal .2 Coupling SFG signal in a fiber. 215 vii Contents C OsO4 -stabilized CO2 laser 217 C.

218 D Means and errors of the frequency measurement 221 E List of line-center frequencies of methanol recorded by direct absorption spectra 223 F Saturated absorption spectra of non-resolved K-doublets 229 G Line-center frequencies and uncertainties of non-assigned rovibrational lines of trioxane 233 viii Introduction Precision spectroscopic experiments on atoms can nowadays reach a fractional ac- curacy of a few part in 1018 level [1] have brought striking results: measurement of fundamental constants [2, 3] and their possible variation in time [4–9], clocks of highest accuracy [10, 11] or probes of general relativity and physics beyond the standard model [12]. Compared to atoms, molecules have a complex internal structure (i. rotational, and vibrational states) and strong intra-molecular fields, making their manipulation and control more complicated than for atoms. However, accurate spectroscopic studies of molecules give insight into many exciting advances in physical chemistry and fundamental physics, although the best spectroscopic precisions achieved with molecules is worse by more than three orders of magnitude than with atoms.

Accurate spectroscopic models are indeed required for improving our knowledge in at- mospheric physics but also for environmental monitoring, and remote sensing greenhouse gases for example [13, 14]. More than 200 molecules have been detected in interstellar and circumstellar clouds, and they are excellent probes of the physical conditions and the history of their environments [15]. A better understanding of the spectra of those species would benefit astrophysics. In addition, molecular spectroscopy is being used in many applications including industrial monitoring, trace gas detection, and medical diagnosis.

Moreover, precise studies on molecules, whether it be neutral species or molecular ions, can play an important role to test fundamental physics, and in particular funda- mental symmetries. Several groups are attempting to measure the electron’s electric dipole moments (EDM), a signature of the violation of a combination of the time and parity symmetry, which is predicted to be very small but non-zero by theories beyond the Standard Model [16]. Diatomic and light radicals have already made a sizeable impact. For instance, recent experiment using heavy molecules (i.

YbF [17], ThO [18] , HfH+ [19]) yield the best limits on the size of the EDM of the electron (de | < 1.1 × 10−29 ), out- performing the limit set by measurements on atoms. Molecular systems can also be used to test the parity symmetry, by measuring, for instance, parity violation (PV) signatures in the spectrum of chiral molecules [20–23]. Due to the parity violation inherent in the weak nuclear interaction, levels of the enantiomers of a chiral molecule are expected to have a tiny energy difference (see section 1.5 of this manuscript) and in turn their spec- trum should exhibit small frequency differences. The latter may be however detectable by the most sensitive experiments.

Molecules are also being used to measure physical and fundamental constants. For in- stance, the Boltzmann constant kB , that plays an important role in the recent redefinition of the Kelvin, has been precisely determined by molecular spectroscopic measurement. Introduction This technique called Doppler broadening thermometry (DBT) consists in measuring accurately the Doppler-broadened absorption spectrum of a molecule to determine the Doppler width and extract kB [24–26]. The first DBT experiment was performed at Laboratoire de Physique des Lasers on the NH3 molecule probed with an ultra-stable CO2 laser [27].

Precise measurements of the electron-to-proton mass ratio (me /mp ), a fundamental constant, is also currently being pursued by carrying out high-resolution spectroscopy of H2 , H2 + and their isotopologue [28, 29, 29–32]. Such measurements also provide stringent tests of quantum electrodynamics and allow one to look for fifth forces or extra dimensions at the molecular scale. Precise molecular spectroscopy has also been and is currently being used to search for physics beyond the standard model by measur- ing possible variations of fundamental constants [33]. For instance, a fractional temporal variation of the proton-to-electron mass ratio of (−3.