The use of infrared-FEL allows adsorbate vibrational spectroscopy by IR-visible sum-frequency generation (SFG) beyond the frequency range accessible by benchtop IR lasers Therefore, we synchronized a frequency doubled mode-locked YAG laser (532 nm) with the CLIO-FEL, which is tuneable from 2 to 175 μm The feasibility is demonstrated by recording SFG-vibrational spectra near 5-μm of the CO adsorbate at the electrochemical interface Pt/HClO4 solution containing CH3OH These spectra indicate the coexistence of linearly and doubly-bounded species This work is a preliminary step towards adsorbate SFG-vibrational spectroscopy at longer wavelengths

Adsorbate vibrational spectroscopy by IR-visible sum-frequency generation using CLIO-FEL: CO from CH3OH electrochemical decomposition on Pt

LBL-29124 Preprint Lawrence Berkeley Laboratory UNIVERSITY OF CALIFORNIA Accelerator & Fusion Research Division Submitted to Science Free-Electron Lasers: Present Status and Future Prospects K.-J. Kim and A. Sessler May 1990 o -h J n . . I._} r-- f\l f[J T' rl! C~j d- C; rr; :::c- or: if' LL LO Ui o Prepared for the U.S. Department or Energy under Contract Number DE-AC03-76SF00098. r~.· .i i'

Free-Electron Lasers: Present Status and Future Prospects

Free-electron lasers as scientific instruments are reviewed. The present status and future prospects are delineated with attention drawn to the size, complexity, availability, and performance capability of this new tool.

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Free-electron lasers - Present status and future prospects

The infrared CLIO FEL has operated as a user facility since mid-1992. About 2400 h of laser beam time are now produced annually, of which 800 h are dedicated to FEL physics and optimisation and 1600 h for laser users. The user beam time is allocated by a programme committee, the demands exceeding the available beam time by a large factor. CLIO spectral range spans 3 to 50 μm and its peak power is several MW in 0.2 to 5 ps long pulses. It is based on a dedicated radiofrequency linear accelerator. The repetition rate of the micropulses can be varied from 32 to 4 ns during 10 μs long macropulses (at up to 50 Hz) and average power up to a few Watt is achievable. Besides the laser facility, CLIO is used internally to study FEL physics. Several new studies have been successfully conducted at CLIO: ultrashort FEL pulses, 2-colors simultaneously generated, undulator step tapering, harmonic generation and self amplified spontaneous emission (SASE) at 5 μm. Several of these studies have resulted in the improvements of the user facility. The application of CLIO are in the following fields: - Semiconductors and quantum wells physics - Near field infrared microscopy - Vibrational energy transfers in molecules in rare gas matrices - Pump-probe study of vibrational relaxation of molecules - Surfaces and interfaces studies by sum frequency generation (“SFG”) - Medicine. Ancillary equipment is provided to the users. In particular optical parametric oscillators (“OPOs”) can provide powerful tunable infrared source between 2 and 8 μm to supplement CLIO.

Activities of the CLIO infrared facility

FELiChEM is a new experimental facility under construction at the University of Science and Technology of China (USTC). Its core device is two free electron laser oscillators generating middle-infrared and far-infrared laser and covering the spectral range of 2.5–200 μm. It will be a dedicated infrared light source aiming at energy chemistry research. We present the brief design of the FEL oscillators, with the emphasis put on the middle-infrared oscillator. Most of the basic parameters are determined and the anticipated performance of the output radiation is given. The first light of FELiChEM is targeted for the end of 2017.

https://iopscience.iop.org/article/10.1088/1674-1137/41/1/018102/pdf

Design of FELiChEM, the first infrared free-electron laser user facility in China

The CLIO collaboration has started in 1986 in order to build an infrared laser at LURE at Orsay. It includes the design and construction of a new FEL dedicated rf linear accelerator. The goal is to make a broadly tunable laser (at least in the range 2–20 μm), of high peak power (MW range), and “medium” average power (a few tens of watts). It will be utilized as a “user facility” as well as for FEL fundamental studies.

The linac uses a gridded disperser cathode gun, a 500 MHz prebuncher, a fundamental buncher and one accelerating section powered by a 3 GHz klystron (with 12 μs long pulses). The final energy will be adjustable between 30 and 75 MeV. The desired characteristics are: peak current >50 A, total energy spread ≈1%, normalized emittance <150πmm mrad. The numerical simulations made with PARMELA indicate that these performances will be reached with an emittance better by a factor of 2–4. The accelerator is followed by an achromatic and nearly isochronous 60° bend. It will allow to select the particles within a given energy spread, before the undulator, and to analyse, with respect to time, their energy distribution after the undulator.

The optical cavity is 4.8 m long (32 ns roundtrip time), compatible with the laser risetime (typically 100 passes) and the klystron pulse length of 12 μs. The undulator is made of two independently adjustable identical parts, 0.96 m long (24 × 4 cm) each; the second one can be tapered. This will allow to optimize both the optical gain and energy extraction at different wavelengths. The laser is scheduled to operate by the end of 1990.

Y. Thiery

Papers

CLIO: Collaboration for an infrared laser at Orsay

Clio: free electron laser in orsay