Infrared free-electron lasers

In 1993, the first ultrafast vibrational echo experiments on condensed matter systems were performed using a free electron laser as the source of temporally short, tunable infrared pulses (11). Recently, the development of Ti sapphire laser-based optical parametric amplifier (OPA) systems has made it possible to produce the necessary pulses to perform vibrational echoes using a tabletop experimental system (12,13). The development and application of ultrafast, IR vibrational echoes and other IR coherent pulse sequences are providing a new approach to the study of the mechanical states of molecules in complex molecular systems such as liquids, glasses, and proteins (14-20). While the spin echo, the photon echo, and the vibrational echo are, in many respects, the same type of experiment, the term vibrational echo is used to distinguish IR experiments on vibrations from radio frequency experiments on spins or vis/UV experiments on electronic states. In this chapter, recent vibrational echo experiments on liquids, glasses, and proteins will be described. 

Zimdars D, Tokmakoff A, Chen S, Greenfield SR, Fayer MD, Smith TL, Schwettman HA. Picosecond infrared vibrational photon echoes in a liquid and glass using free electron laser. Phys Rev Lett 1993 70 2718-2721. 

Hill JR, Tokmakoff A, Peterson KA, Sauter B, Zimdars D, Dlott DD, Fayer MD. Vibrational dynamics of carbon monoxide at the active side of myoglobin picosecond infrared free-electron laser pump-probe experiments. J Phys Chem 1994 98 11213-11219. 

A special type of measurement is that of ions in the gas phase by intense radiation which causes electron detachment and the absorption spectrum is detected through the deionized molecules it produces. Such radiation sources are either a high-intensity near-infrared laser [12] or infrared radiation from a free-electron laser [21]. 

Four of the most powerful methods presently applied to elucidate metal cluster geometric structure will be presented in the following. These are mass-selected negative ion photoelectron spectroscopy, infrared vibrational spectroscopy made possible by very recent advances in free electron laser (FEL) technology, gas-phase ion chromatography (ion mobility measurements), and rf-ion trap electron diffraction of stored mass-selected cluster ions. All methods include mass-selection techniques as discussed in the previous section and efficient ion detection schemes which are customary in current gas-phase ion chemistry and physics [71]. 

Keywords biopolymer, far infrared, free electron laser, collective modes, sub-millimeter wave, terahertz... 

Provided that samples can be removed from the laboratory, there are two alternative sources of infrared radiation that are far better than incandescent sources for mid-IR microspectroscopy, namely the synchrotron and the free electron laser (FEE) [16]. 

Williams, G.P. (2001) Synchrotron and free electron laser sources of infrared radiation, in Handbook of Vibrational Spectroscopy, Vol. 1 (eds J.M. Chalmers and P.R. Griffiths), John Wiley Sons, Ltd, Chichester, UK, pp. 341-8. 

The experiments described here were performed on a guided ion beam tandem mass spectrometer [18] that was temporarily installed at the free electron laser facility FELIX (free electron laser for infrared experiments, FOM Institute for Plasma Physics, Nieuwegein, The Netherlands) [19]. A schematic of the experimental setup is shown in Fig. 3.2. Ions are generated in the ion source region (not... 

Transition radiation is considerably weaker than Cerenkov radiation, however since it is a surface phenomenon it avoids problems with radiator thickness and reflections inherent to Cerenkov-generating silica plates. Optical TR can be measured using a streak camera. An optical TR system has been used to time-resolve the energy spread of an electron macropulse in a free-electron laser facility [10]. Interferometry of coherent, far-infrared TR has been used to measure picosecond electron pulse widths and detect satellite pulses at the UCLA Satumus photoinjector, using charges on the order of 100 pC [11],... 

Because of experimental limitations, most of the infrared studies have dealt with rate measurements at energies in the 3000 cm region. However, as longer wavelength and intense infrared lasers become available (e.g., free electron lasers) it should... 

Cramer, R., Hillenkamp, H., and Haglund, R. F. Jr., Infrared Matrix-Assisted Laser Desorption and Ionization by Using a Tunable Mid-Infrared Free-Electron Laser, /. Am. Soc. Mass Spectrom., 7, 1187, 1996. 

Fukui, K. Takada, Y. Sumiyoshi, T. Imai, T. Takahashi, K. Infrared multiphoton dissociation spectroscopic analysis of peptides and oligosaccharides by using Fourier transform ion cyclotron resonance mass spectrometry with a midinfrared free-electron laser. J. Phys. Chem. B. 2006,110, 16111-16116. 

VaUe, J.J. Eyler, J.R. Oomens, J. Moore, D.T. van der Meer, A.F.G. von Helden, G. Meijer, G. Hendrickson, C.L. Marshall, A.G. Blakney, G.T. Free electron laser-Fourier transform ion cyclotron resonance mass spectrometry facility for obtaining infrared multiphoton dissociation spectra of gaseous ions. Rev. Sci. Instrum. 2005, 76.023103. 

H. Monobe, K. Kiyohara, N. Terasawa, M. Heya, K. Awazu, Y. Shimizu, Infrared photoinduced alignment change for triphenylene-based columnar liquid crystals by using free electron laser. Thin Solid Films 438-439, 418-422 (2003)... 

The resmgence of interest in the concept that began in the mid-1970s followed two paths. The term free-electron laser was coined in 1975 by John Madey to describe an experiment at Stanford University that used an electron beam from a radio-frequency hnear accelerator (rf linac). This experiment produced stimulated emission in the infrared spectrum at a wavelength of 10.6 /um using an electron beam from a radio-frequency hnear accelerator (rf Unac). 

Commercial applications have been proposed that use high average power free-electron lasers to heat the surface of polymers for enhancements to the surface morphology. This uses infrared at 5.8 to 6.2-/rm wavelengths where high absorption results from carbonyl-related molecular absorption bands. By enhancing surface roughness in polyester and nylon fibers, the fabrics can be made softer, hydrophilic, and the material more readily accepts dyes. 

---