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Superfluorescence, superradiance, and free-induction decay observed following the excitation of helium atoms and ions with FEL pulses from SACLA BL1

ハリーズ ジェームズ, ハリーズ ジェームズ

Published Sep 11, 2017• 0 citations
OpenAlex

Abstract

Using EUV pulses from SACLA BL1 free-electron laser, we have successfully observed superfluorescence at wavelengths of 469 nm and 164 nm from a dense sample of excited helium ions, created by (1+1)-photon ionisation/excitation. The results of related numerical simulations will also be reported.

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Observation of superfluorescence at a wavelength of 164 nm from ‘highly’ - charged helium ions

ハリーズ ジェームズ, ハリーズ ジェームズ

Using EUV pulses from SACLA BL1 free-electron laser, we have successfully observed superfluorescence at wavelengths of 469 nm and 164 nm from a dense sample of excited helium ions, created by (1+1)-photon ionisation/excitation. The results of related numerical simulations will also be reported.

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Detailed study of superfluorescence at a wavelength of 469 nm from helium ionised and excited using free-electron laser pulses

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We have studied in detail the emission of superfluorescence at a wavelength of 469 nm (4p→3s) from helium ions created and excited using free-electron laser pulses from SACLA’s BL1. In earlier work we observed superfluorescence at visible wavelengths in neutral helium [1-5]. To observe superfluorescence from helium ions we used a wavelength of 24.3 nm, resonant with the He + 1s→4p transition and sufficiently short to ionise neutral helium atoms. The density of excited He + ions created by this sequential 2-photon absorption was sufficient to allow for the development of superfluoresence.

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ヘリウムイオンの FEL 励起に伴う超蛍光、ヨーク超蛍光、自由誘 導減衰、四光波混合

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We report the observation of superfluorescence at wavelengths of 469 nm, 164 nm and 30.4 nm from helium ions created and excited using pulses from the EUV free-electron laser at SACLA BL1. Experimental observations of intense, highly-directional emission (all 3 wavelengths) and a 1/(density) pulse delay dependence (469 nm emission), along with a detailed numerical simulation support our interpretations.

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EUV-FEL 励起由来のヘリウムイオンからの 164 nm 超蛍光の観測

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We report the probable observation of superfluorescence at a wavelength of 164 nm from helium ions created and excited using pulses from the EUV free-electron laser at SACLA BL1. The emission is the second step of a superfluorescence cascade from excited 4p states. To our knowledge this is the shortest wavelength at which superfluoresence has ever been demonstrated. The high intensity of the emission and the narrow angular divergence strongly support the interpretation as superfluorescence, and numerical simulations will also be presented which support this.

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Extreme ultraviolet superfluorescence from helium ions

ハリーズ ジェームズ, James Harries

We report the observation of superfluorescence at wavelengths of 469 nm, 164 nm and 30.4 nm from helium ions created and excited using pulses from the EUV free-electron laser at SACLA BL1. The observations at 164 nm and 30.4 nm represent the first ever observations at such short wavelengths.

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Observation of extreme ultraviolet superfluorescence from helium atoms ionised and excited using soft x-ray free-electron laser pulses

ハリーズ ジェームズ, James Harries

We have studied the propagation of free-electron laser pulses at a wavelength of 24.3 nm through a dense sample of helium gas. Ionisation and resonant excitation leads to strong population of the He+ 4p state, and the resulting superfluorescence, yoked superfluorescence, and free-induction decay were observed experimentally. Numerical simulations using the Maxwell-Liouville equations were used to interpret the observations.

•Jul 24, 2019•0 citations
We have studied in detail the emission of superfluorescence at a wavelength of 469 nm (4p→3s) from helium ions created and excited using free-electron laser pulses from SACLA’s BL1. In earlier work we observed superfluorescence at visible wavelengths in neutral helium [1-5]. To observe superfluorescence from helium ions we used a wavelength of 24.3 nm, resonant with the He + 1s→4p transition and sufficiently short to ionise neutral helium atoms. The density of excited He + ions created by this sequential 2-photon absorption was sufficient to allow for the development of superfluoresence.
We report the probable observation of superfluorescence at a wavelength of 164 nm from helium ions created and excited using pulses from the EUV free-electron laser at SACLA BL1. The emission is the second step of a superfluorescence cascade from excited 4p states. To our knowledge this is the shortest wavelength at which superfluoresence has ever been demonstrated. The high intensity of the emission and the narrow angular divergence strongly support the interpretation as superfluorescence, and numerical simulations will also be presented which support this.