Pulse overlap artifacts and double quantum coherence spectroscopy

Summary, in English

The double quantum coherence (DQC) signal in nonlinear spectroscopy gives information about the many-body correlation effects not easily available by other methods. The signal is short-lived, consequently, a significant part of it is generated during the pulse overlap. Since the signal is at two times the laser frequency, one may intuitively expect that the pulse overlap-related artifacts are filtered out by the Fourier transform. Here, we show that this is not the case. We perform explicit calculations of phase-modulated two-pulse experiments of a two-level system where the DQC is impossible. Still, we obtain a significant signal at the modulation frequency, which corresponds to the DQC, while the Fourier transform over the pulse delay shows a double frequency. We repeat the calculations with a three-level system where the true DQC signal occurs. We conclude that with realistic dephasing times, the pulse-overlap artifact can be significantly stronger than the DQC signal. Our results call for great care when analyzing such experiments. As a rule of thumb, we recommend that only delays larger than 1.5 times the pulse length should be used.

• Author: Albin Hedse; Alex Arash Sand Kalaee; Andreas Wacker; Tõnu Pullerits
• Department/s: LU Profile Area: Light and Materials; LTH Profile Area: Nanoscience and Semiconductor Technology; Chemical Physics; NanoLund: Centre for Nanoscience; Mathematical Physics; LTH Profile Area: Photon Science and Technology; eSSENCE: The e-Science Collaboration
• Publishing year: 2023-04
• Language: English
• Publication/Series: Journal of Chemical Physics
• Volume: 158
• Issue: 14
• Links: http://dx.doi.org/10.1063/5.0146148
• Document type: Journal article
• Publisher: American Institute of Physics (AIP)
• Topic: Atom and Molecular Physics and Optics; Signal Processing
• Status: Published
• ISBN/ISSN/Other: ISSN: 0021-9606