Infrared Free Electron Laser Research Articles

Enrichment of Silicon Isotopes with Infrared Free-Electron Laser Radiation

We have used the FELIX infrared free-electron laser (FEL) at the FOM Institute for Plasma Physics in The Netherlands to enrich silicon isotopes by multiple-photon dissociation of the molecule Si2F6. The absorption of infrared radiation induces the reaction Si2F6 → SiF4 + SiF2. Much of the SiF2 product further reacts to form additional SiF4. The Si2F6 molecule has absorption bands in the 10, 12, and 25 μm spectral regions. FEL-induced reactions occurred in all three regions. The reaction fraction was highest for the stronger band in the 10 μm region. Reactions in all three bands were isotopically selective. Irradiation in the 10 μm region at 952 cm-1 gave an isotopic selectivity of 5.6 for 30Si. For comparison, the published isotopic selectivity using a CO2 laser in the same spectral region is in excess of 17. We attribute the lower selectivity obtained with an FEL to its longer macropulse, its broader spectral width, and differences in experimental procedure. FEL irradiation in the region of the 12 μm ban...

Silicon nanostructure fabrication using IR-FELs and its optical properties

Novel silicon nanostructures were fabricated from hydrogenated amorphous silicon (a-Si:H) by irradiation with infrared Free Electron Lasers (IR-FELs). SEM and XTEM observations and Raman spectra show that the fabricated materials have nanometer or micrometer-sized complicated fibers (Si microfibers) including large amounts of several nanometer-sized Si nanocrystals (nc-Si) embedded in the glassy SiO 2 matrices. Size dependent visible photoluminescence (PL) from nc-Si in the Si microfibers was observed at room temperature. The visible PL mechanism of nc-Si and formation mechanism of the Si microfibers due to the FEL irradiation are discussed.

Raman and FT-IR studies of photodynamic processes of cholesteryl oleate using IRFELs

Chemical bond-changes of cholesteryl oleate in infrared free electron laser (IRFEL) photodynamic processes were examined by Raman spectroscopy and Fourier transform infrared microspectroscopy (FT-IR) as a function of the FEL exposure time. We found that the exposure of 5.79 μm-FELs induces not only dissociation of ester (RCOOR′) bonds but also the chemical changes from the ester (RCOOR′) bonds to aldehyde (RCHO), carboxylic acid (RCOOH), carboxylate (RCOO −) or ketone (R 2CO) bonds.

Industrial applications of the Jefferson Lab high-power free-electron laser

In partnership with the US Navy, high-technology corporations, and research universities, Jefferson Lab is building a superconducting radio-frequency (SRF) accelerator-driven free-electron laser (FEL) and is outfitting an FEL user facility. This first fourth-generation light source – a 1 kW, 3 μm infrared (IR) laser – is the first step in a program to develop high-average-power SRF-based IR and ultraviolet (UV) FELs for multiple manufacturing applications as well as for defense-related applied research and basic scientific research. This initial FEL will be driven by a 42 MeV, 5 mA recirculating SRF linac similar to the much larger SRF linac in Jefferson Lab's 4 GeV, 200 μA Continuous Electron Beam Accelerator Facility (CEBAF). The FEL is expected to demonstrate 75% energy recovery. Its linac will be cooled by the existing CEBAF cryogenic system. At Jefferson Lab, an infrastructure of facilities and people already supports the advance of SRF and closely related technologies in the furtherance of the lab's primary mission of nuclear and particle physics. This paper summarizes the opportunity represented by SRF-driven FELs and reports on the program now underway to develop them.

Effects of the axial magnetic field component on the electron trajectory in the wiggler section

A section of a wiggler with SmCo/sub 5/ magnets was designed to be utilized in an infrared free-electron laser (IRFEL). The choice of low-cost small magnets resulted in a small gap in the wiggler (/spl les/10.0 mm). This gap size accentuated the edge effects, thus making the profile of the magnetic field more susceptible to distortion. The solution of the magnetic field component was obtained from finite-element computer codes and measurements of the magnetic field distribution in the inner region of the wiggler were performed. Effects of the axial magnetic field component on the electron beam trajectories were studied using a single-particle model neglecting collective effects.

First lasing of the compact infrared free-electron laser

On 15 May 1996, lasing was achieved at the Compact Infrared Free-Electron Laser (CIRFEL) at 14 μm. The electron beam energy was 11.2 MeV and the micropulse charge was 1 nC. The width of the detuning curve was approximately 50 μm. Since achieving this milestone, we have lased repeatedly from 12.5 to 20 μm with between 0.25 and 1.5 nC of charge. Saturation is typically reached in less than 1.5 μs. The measured FEL spectrum is Gaussian in shape with a line width of 56 nm at 13 μm. Assuming a transform limited pulse, this corresponds to an FEL light pulse of 4.4 ps. The CIRFEL is a photocathode based free-electron laser with a micropulse width of 4–10 ps and a micropulse separation of 7 ns. The macropulse length is between 4 and 6 μs and the repetition rate is between 1 and 5 Hz. We present details of the CIRFEL machine as well as experimental measurements of the FEL radiation.

Vibrational Dynamics of Carbon Monoxide at the Active Site of Myoglobin: Picosecond Infrared Free-Electron Laser Pump-Probe Experiments

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVibrational Dynamics of Carbon Monoxide at the Active Site of Myoglobin: Picosecond Infrared Free-Electron Laser Pump-Probe ExperimentsJeffrey R. Hill, A. Tokmakoff, Kristen A. Peterson, B. Sauter, D. Zimdars, Dana D. Dlott, and M. D. FayerCite this: J. Phys. Chem. 1994, 98, 43, 11213–11219Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October 1994https://doi.org/10.1021/j100094a032RIGHTS & PERMISSIONSArticle Views376Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts

An infrared free electron laser system for the proposed chemical dynamics research laboratory at LBL based on a 500 MHz superconducting linac

We describe a new design of the Infrared Free Electron Laser (IRFEL) for the proposed Chemical Dynamics Research Laboratory (CDRL) at LBL. The design and choice of parameters are dictated by the unique requirements of the CDRL scientific program. The accelerator system is based on the 500 MHz superconducting cavity technology to achieve a wavelength stability of 10 −4.

Simulation of Tunable Infra-Red Free-Electron Laser Based on Test Linac of Pohang Accelerator Laboratory

We have investigated the possibility of tunable Infrared Free-Electron Laser with Test Linac of Pohang Accelerator Laboratory through one dimensional simulation which includes energy spread and space charge effects and 3-D particle simulation that ignores space charge force but takes into account the energy spread and the emittance of the electron beam and the diffraction of the electromagnetic wave. The enhanced current density of the Test Linac makes it feasible to amplify the 4.2 kW signal of 10.6 µm radiation to 200 MW level. Extending the design parameters, electron beam energy (20∼60 MeV), wiggler field strength (around 3 kG), and radiation wavelength (10∼90 µm), we have revealed the requisites for the design of the tunable radiation source and the expected gains in that frequency range. It is shown to generate more than 100 MW in the tunable range.

Design overview of a highly stable infrared free electron laser at LBL

An infrared free electron laser (IRFEL) is being designed for the Chemical Dynamics Research Laboratory (CDRL) at LBL. The FEL is based on a 50 MeV rf linac operating in synchronization to the Advanced Light Source (ALS), and will produce intense (100 μJ per micropulse), narrow bandwidth (narrower than 0.1%) radiation between 3 and 50 μm. In the design, we pay particular attention to the FEL stability issues and require that the fluctuations in electron beam energy and in timing be less then 0.05% and 0.1 ps, respectively. The FEL spectrum can then be stabilized to about 10 −3, or if grating is used, to 10 −4. We discuss various sources of fluctuations in the gun, the bunchers and the accelerator sections, as well as the feedback and feedforward schemes to reduce these fluctuations. The accelerator structure is chosen to be of the side-coupled, standing-wave type for easier control. The beam transport is made isochronous to avoid the coupling between the energy and the timing fluctuations.

Infrared free-electron laser as a probe of vibrational dynamics on surfaces

The infrared free-electron laser (IRFEL) is a useful light source that can be employed as a probe of vibrational dynamics on surfaces. We explore in detail two possible applications of the IRFEL. One type of experiment utilizes the IRFEL to measure vibrational relaxation on surfaces directly, using infrared saturation and ground-state recovery techniques. The second application uses the IRFEL to desorb adsorbates from surfaces by resonantly exciting their vibrational modes. This application is illustrated by recent investigations of the resonant desorption of butane from Al2O3(11 2¯0), using the Mark III IRFEL. These studies revealed a greater desorption yield for the asymmetric C—H stretches in comparison with the symmetric C—H stretches. This greater desorption efficiency for the asymmetric C—H stretches was attributed to the orientation of the butane molecules in an ordered adlayer on Al2O3(11 2¯0). Future applications of the IRFEL as a probe of vibrational dynamics on surfaces are also discussed.