Dual-Laser Spectrometer

• Subject Area: Physical Chemistry
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 573573612

Before his appointment as a professor of Experimental Physics at the RPTU, the head of the applying research group has led significant contributions to laser-based infrared (IR) vibrational spectroscopy, in particular harnessing the control over the oscillations of broadband IR light. The laser infrastructure for which funding is requested here will constitute the basis for the main research of the new Optical Quantum Metrology working group, thereby enabling a continuation of these efforts. We plan to use the infrastructure for consolidating and further developing our core competences in IR spectroscopy in general, and field-resolved spectroscopy (FRS) in particular, at RPTU. In addition, the new spectroscopic infrastructure will be used in exploratory collaborations. To this end, we opt for a high-power two-channel femtosecond laser architecture, the initial pulses of each channel being generated by an independent modelocked oscillator with a pulse repetition frequency of >75 MHz. This system will provide the basis for ultrabroadband spectral coverage, ranging from the near-IR to the far-IR/terahertz regions. The choice of a dual-oscillator configuration provides the highest flexibility for spectroscopic schemes involving fast scanning. The intended scientific use can be structured in three areas: (i) Exploration of the fundamental limits of sensitivity, dynamic range, and speed in IR spectroscopy. This basic-research topic in the field of laser spectroscopy constitutes the core competence of the applying working group. Using the requested infrastructure, we will investigate which spectroscopy scheme is most suitable in each spectral range, and develop a quantitative understanding for the amount of information on biological samples (in particular biological gases and cells) that can be extracted with scanning spectroscopy. (ii) Implementation of high-throughput IR-spectroscopy-based single-cell flow cytometry. Using the understanding from (i) we will implement the first broadband non-destructive, label-free and chemically-specific flow cytometer at RPTU, with measurement times as low as 1 ms/cell. In close collaboration with the Department of Biology, we will investigate the performance of our new method in a series of experiments aiming at providing deeper and faster insights into cellular function and distribution. These include the assessment of cell fitness and the identification of circulating cancer cells among healthy cells. (iii) Implementation of high-dynamic-range and high-spectral-resolution measurements of biological gases. With the same spectroscopy infrastructure, high-resolution measurements of gases will become possible. After assessing the performance of our spectrometer with synthetic gas samples, we plan pilot experiments in close collaboration with the Department of Biology. These include the identification of breath-based biomarkers for Alzheimer’s disease and the analysis of the pathogen-induced plant volatilome.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Doppel-Laser-Spektrometer
• Instrumentation Group: 5700 Festkörper-Laser
• Applicant Institution: Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau
• Leader: Professor Dr. Ioachim Pupeza