Dr. Ibrahim Sadiek
Ruhr-Uni Bochum/INP Greifswald
spricht zum Thema
Mid-Infrared Frequency Combs for Precision Spectroscopy
Abstract:
Advancements in frequency comb technology have created new opportunities in broadband precision molecular spectroscopy. As coherent broadband light sources, frequency combs have significantly improved the performance of traditional broadband spectroscopic techniques in terms of spectral resolution, frequency accuracy, and sensitivity. For example, combining frequency combs with mechanical Fourier transform spectrometers (FTS) reduces acquisition times by orders of magnitude compared to conventional FTS using incoherent light sources. Alternatively, dual comb spectroscopy – using two combs with slightly different repetition rates that heterodyne on a photodiode – enables broadband absorption measurements at video-rate speeds. Furthermore, optical dispersive techniques with frequency combs allow spectral recording on the microsecond timescale, limited only by the camera integration time and without mechanical moving parts.
Here, we present direct comb-based detection methods we developed:1. a comb-based Fourier transform spectrometer, and 2. cross-dispersive Virtually Imaged Phased Array (VIPA) spectrometer. We applied these detection methods, along with dual-comb spectroscopy, for precision spectroscopic measurements of halogenated volatile organic compounds (some with line parameters now in the HITRAN database) [1, 2], isotope-resolved measurements on nitrous oxide (aiming to establish so far lacking isotopomer standard), and reactive molecular plasmas [3, 4]. The broadband width and the high-resolution capabilities of comb spectroscopy provide detailed quantum-state-resolved insights that were previously unattainable with conventional absorption techniques using tunable lasers.
[1] I. Sadiek, A. Hjältén, F. Senna Vieira, C. Lu, M. Stuhr, A. Foltynowicz, J. Quant. Spectrosc. Radiat. Transfer 2020, 255, 107263;
[2] I. Sadiek, A. Hjälten, F. C. Roberts, J. H. Lehman, A. Foltynowicz, Phys. Chem. Chem. Phys. 2023, 25, 8743;
[3] I. Sadiek, A. Puth, G. Kowzan, A. Nishiyama, S.-J. Klose, J. Röpcke, N. Lang, P. Maslowski, J. H. van Helden, Plasma Sources Sci. Technol. 2024, 33, 075011;
[4] I. Sadiek, A. J. Fleisher, J. Hayden, X. Huang, A. Hugi, R. Engeln, N. Lang, J. H. van Helden, Commun. Chem. 2024, 7, 110.
Interessenten sind herzlich eingeladen
Professor Dr. Brandenburg
Wann: 14.01.2025 14:00
Wo: Institute für Physik, Hörsaal 2