We show that the distribution of quantum numbers of Rydberg states does not
only depend on the field strength and wavelength of the laser which the atom is
exposed to, but that it also changes significantly with the duration of the
laser pulse. We provide an intuitive explanation for the underlying mechanism
and derive a scaling law for the position of the peak in the quantum number
distribution on the pulse duration. The new analytic description for the
electron's movement in the superposed laser and Coulomb field (applied in the
study of quantum numbers) is then used to explain the decrease of the Rydberg
yield with longer pulse durations. This description stands in contrast to the
concepts that explained the decrease so far and also reveals that
approximations which neglect Coulomb effects during propagation are not
sufficient in cases such as this.Comment: 8 pages, 8 figure

Hofmann, C.

I. A. Ivanov

Landsman, A.S.

Ortmann, L.

English

arXiv

© 2021 American Physical Society.High-order harmonic generation (HHG) creates coherent high-frequency radiation via the process of strong field ionization followed by recombination. Recently, a complementary approach based on frustrated tunnel ionization (FTI) was demonstrated [Yun et al., Nat. Photon. 12, 620 (2018)1749-488510.1038/s41566-018-0255-8]. It uses spectrally separated peaks created by lower quantum number Rydberg states to produce coherent extreme ultraviolet (EUV) light. While much is understood about enhancing emission from HHG by controlling recombining electron trajectories, relatively little is known about controlling the quantum number distribution of Rydberg states. This distribution is generally believed to be determined primarily by field strength and laser frequency. We show that, in fact, it also changes significantly with the duration of the laser pulse: Increasing pulse duration depletes lower lying Rydberg states, thereby substantially decreasing EUV yield. Using electron trajectory analysis, we identify elastic recollision as the underlying cause. Our results open the door to greater control over production of coherent high-frequency radiation, by combining FTI and HHG mechanisms, and also improved the interpretation of molecular imaging experiments that rely on elastic electron recollision.11Nsciescopu

IBS Publications Repository

Controlling quantum numbers and light emission of Rydberg states via the laser pulse duration

High-order harmonic generation (HHG) creates coherent high-frequency radiation via the process of strong field ionization followed by recombination. Recently, a complementary approach based on frustrated tunnel ionization (FTI) was demonstrated [Yun et al., Nat. Photon. 12, 620 (2018)]. It uses spectrally separated peaks created by lower quantum number Rydberg states to produce coherent extreme ultraviolet (EUV) light. While much is understood about enhancing emission from HHG by controlling recombining electron trajectories, relatively little is known about controlling the quantum number distribution of Rydberg states. This distribution is generally believed to be determined primarily by field strength and laser frequency. We show that, in fact, it also changes significantly with the duration of the laser pulse: Increasing pulse duration depletes lower lying Rydberg states, thereby substantially decreasing EUV yield. Using electron trajectory analysis, we identify elastic recollision as the underlying cause. Our results open the door to greater control over production of coherent high-frequency radiation, by combining FTI and HHG mechanisms, and also improved the interpretation of molecular imaging experiments that rely on elastic electron recollision

Ivanov, I.

Landsman, A.

MPG.PuRe

High-order harmonic generation (HHG) creates coherent high-frequency radiation via the process of strong field ionization followed by recombination. Recently, a complementary approach based on frustrated tunnel ionization (FTI) was demonstrated [Yun et al., Nat. Photon. 12, 620 (2018)1749-488510.1038/s41566-018-0255-8]. It uses spectrally separated peaks created by lower quantum number Rydberg states to produce coherent extreme ultraviolet (EUV) light. While much is understood about enhancing emission from HHG by controlling recombining electron trajectories, relatively little is known about controlling the quantum number distribution of Rydberg states. This distribution is generally believed to be determined primarily by field strength and laser frequency. We show that, in fact, it also changes significantly with the duration of the laser pulse: Increasing pulse duration depletes lower lying Rydberg states, thereby substantially decreasing EUV yield. Using electron trajectory analysis, we identify elastic recollision as the underlying cause. Our results open the door to greater control over production of coherent high-frequency radiation, by combining FTI and HHG mechanisms, and also improved the interpretation of molecular imaging experiments that rely on elastic electron recollision

Ortmann, L

Hofmann, C

Ivanov, IA

Landsman, AS

UCL Discovery

https://discovery.ucl.ac.uk/id/eprint/10152680/1/PhysRevA.103.013104.pdf

Controlling the quantum number distribution and yield of Rydberg states via the duration of the laser pulse

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