Mid-infrared lasers

In this contribution we demonstrate vibrationally induced molecular dissociation in two polyatomic molecules, namely chromium hexacarbonyl and diazomethane (Fig. 1), employing fs mid-infrared laser sources [1,2]. As will be shown below, in both cases the initially excited mode does not lead directly to reaction but provides the doorway to access the right combination of modes. Thus both reactions have three steps (1) Stepwise multiphoton excitation of the doorway mode, (2) sharing of energy with other modes, and (3) formation of... 

Nelson, J.S., et al. 1991. Mid-infrared laser ablation of stratum comeum enhances in vitro percutaneous transport of drugs. J Invest Dermatol 97 874. 

We now describe briefly the FIR laser magnetic resonance studies of the four molecules listed above. FeH has also been studied by mid-infrared laser magnetic resonance, and NiH by microwave/optical double resonance these investigations are discussed elsewhere. 

The apparatus used to perform vibrational relaxation experiments in supercritical fluids consists of a picosecond mid-infrared laser system and a variable-temperature, high-pressure optical cell (68,73). Because the vibrational absorption lines under study are quite narrow (<10 cm-1), a source of IR pulses is required that produces narrow bandwidths. To this end, an output-coupled, acousto-optically Q-switched and mode-locked Nd YAG laser is used to synchronously pump a Rhodamine 610 dye laser. The Nd YAG laser is also cavity-dumped, and the resulting 1.06 pm pulse is doubled to give an 600 u.l pulse at 532 nm with a pulse duration of "-75 ps. The output pulse from the amplified dye laser ("-35 uJ at 595 nm, 40 ps FWHM) and the cavity-dumped, frequency-doubled pulse at 532 nm... 

Mid-infrared laser ablation of the SC has been used to allow the transdermal delivery of interferon-y. The mechanism by which this laser beam explodes away the SC is complex, yet quite reproducible and controllable, in that the number of laser pulses is correlated to the degree of SC damage (and hence to the peptide s permeability through the tissue). Tissue destruction below the SC appeared to be minimal. 

THEORETICAL COMPARISON OF DILUTE-NITRIDE "W" AND "M" InAsN/GaSb MID-INFRARED LASER DIODES... 

P. Werle, Near-and mid-infrared laser-optical sensors for gas analysis, Optics and Laser Eng., 37 101-114(2002). 

Wilier, U., Saraji, M., Khorsandi, Geiser, R, Schade, W. "Near- and Mid-Infrared Laser Monitoring of Industrial Processes, Environment and Security Applications. " Optics and Lasers in Engineering 44 (2006) 699-710. 

The NiH radical has been studied quite thoroughly, by FIR laser magnetic resonance as described here [76], but also by microwave/optical double resonance and by mid-infrared laser magnetic resonance, discussed elsewhere. 

A. Hinz, J. Pfeiffer, W. Bohle, W. Urban, Mid-infrared laser magnetic resonance using the Faraday and Voigt effects for sensitive detection. Mol. Phys. 45,1131 (1982)... 

Yu S, Li D, Chong H, Sun C, Yu H, Xu K (2014) In vitro glucose measurement using tunable mid-infrared laser spectroscopy combined with fiber-optic sensor. Biomed Opt Exp 5 275-286... 

Pauling L (1960) The nature of the chemical bond, 3rd edn. Cornell Univ Press, Ithaca Liu Y, Guo Y, Lin 1 et al (2001) Measurement of the electric dipole moment of NO by mid-infrared laser magnetic resonance spectroscopy. Mol Phys 99 1457-1461 Coulson CA (1942) The dipole moment of the C-H bond. Trans Faraday Soc 38 433-444 Rayane D, Allouche A-R, Antoine R et al (2003) Electric dipole of metal-benzene sandwiches. Chem Phys Lett 375 506-510... 

Several other ionization methods and MS technologies have been investigated for possible use for imaging. Atmospheric pressure infrared MALDI (AP IR-MALDI) and mid-infrared laser ablation with electrospray ionization (LAESI) have been reported and use focused laser radiation for ambient sampling with no sample preparation or chemical modification required. In these... 

Werle P (1998) A review of recent advances in semiconductor laser based gas monitors. Spectrosc Acta A 54 197-236 Werle P, Slemr F, Maurer K, Kormann R, Mucke R, Janker B (2002) Near- and mid-infrared laser-optical sensors for gas analysis. Opt Lasers Eng 37 101-114... 

Th. Topfer, K.P. Petrov, Y. Mine, D. Jrmdt, R.F. Curl, F.K. Tittel Room-temperature mid-infrared laser sensor for trace gas detection. Appl. Opt. 36, 8042 (1997)... 

Condon, N.J., O Cormor, S., Bowman, S.R., 2006. Growth and characterization of single-crystal Er KPb2Cl5 as a mid-infrared laser material. J. Cryst. Growth 291 (2), 472-478. 

Seefeld K, Brause R, Haber T, Kleinermanns K (2007) hnino tautomers of gas-phase guanine from mid-infrared laser spectroscopy. J Phys Chem A 111 6217-6221... 

Sripadi, P. Nazarian, J. Hathout, Y. Hoffman, E.P. Vertes, A. In Vitro Analysis of Metabolites from the Untreated Tissue of Torpedo Califomica Electric Organ by Mid-Infrared Laser Ablation Electrospray Ionization Mass Spectrometry. Metaholomics 2009, 5, 263-276. 

Ben-David M, Croitom NI, Inbetg A, Revsin G, Gannot I. Electroless deposited broadband omnidirectional multilayer reflectors for mid-infrared lasers. SPIE-Int. Soc. Opt. Eng. Proceedings of Spie - the International Society fen- Optical Engineering, vol.4616, 2002, pp.97-I04... 

Speaking generally, it may be stated that optical pumping of the molecules we will consider takes place via vibrational transitions (with associated small rotational energy shifts) while the more closely spaced rotational transitions themselves are responsible for the (sub)mm laser action. The exception to this is provided by a class of mid-infrared lasers whose emission, as well as absorption, takes place on vibrational-rotational transitions [2.5]. In only one case, to my knowledge, has a vibrational band been proposed as the mechanism for (sub)mm laser action [2.6]. 

O.Y.F. Henry, S.A. Piletsky and D.G. GuUen, Fabrication of molecularly imprinted polymer microarray on a chip by mid-infrared laser pulse initiated polymerisation, Biosens. Bioelectron., 23 (12) 1769-1775, 2008. 

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