Jet-cooling

Fehrensen B, Hippier M and Quack M 1998 Isotopomer selective overtone spectroscopy by ionization detected IR + UV double resonance jet-cooled aniline Chem. Phys. Lett. 298 320-8... 

Boyarkine O V, Settle RDF and Rizzo T R 1995 Vibrational overtone spectra of jet-cooled CFgH by infrared laser assisted photofragment spectroscopy Ber. Bunsenges. Rhys. Chem. 99 504-13... 

Uracil, thymine, and cytosine have been studied using this technique (89JA2308 and references therein). For uracil and thymine, the dioxo tautomer predominates in the case of cytosine (70), three tautomers were detected, 70a, 70b, and 70c, the last one being the least abundant. The gas-phase tautomeric equilibrium of 2-pyridone 15a and 2-hydroxypyridine 15b has been studied by MW spectroscopy (93JPC46) using both a conventional spectrometer and a jet-cooled millimeter-wave spectrometer. The relative abundances are 3 1 in favor of the hydroxy form 15b, which exists in the Z conformation shown (Scheme 23). 

Bishea, G.A. and Morse, M.D. (1991) Spectroscopic studies of jet-cooled AgAu and Au2. Journal of Chemical Physics, 95, 5646-5659. 

Morse, M.D., Hopkins, J.B., Langridge-Smifh, P.R.R. and Smalley, R.E. (1983) Spectroscopic studies of the jet-cooled copper trimer./oitmai of Chemical Physics, 79, 5316-5328. 

This chapter deals mainly with (multi)hyphenated techniques comprising wet sample preparation steps (e.g. SFE, SPE) and/or separation techniques (GC, SFC, HPLC, SEC, TLC, CE). Other hyphenated techniques involve thermal-spectroscopic and gas or heat extraction methods (TG, TD, HS, Py, LD, etc.). Also, spectroscopic couplings (e.g. LIBS-LIF) are of interest. Hyphenation of UV spectroscopy and mass spectrometry forms the family of laser mass-spectrometric (LAMS) methods, such as REMPI-ToFMS and MALDI-ToFMS. In REMPI-ToFMS the connecting element between UV spectroscopy and mass spectrometry is laser-induced REMPI ionisation. An intermediate state of the molecule of interest is selectively excited by absorption of a laser photon (the wavelength of a tuneable laser is set in resonance with the transition). The excited molecules are subsequently ionised by absorption of an additional laser photon. Therefore the ionisation selectivity is introduced by the resonance absorption of the first photon, i.e. by UV spectroscopy. However, conventional UV spectra of polyatomic molecules exhibit relatively broad and continuous spectral features, allowing only a medium selectivity. Supersonic jet cooling of the sample molecules (to 5-50 K) reduces the line width of their... 

Kim NJ, Jeong G, Kim YS, Sung J, Kim SK, Park YD (2000) Resonant two-photon ionization and laser induced fluorescence spectroscopy of jet-cooled adenine. J Chem Phys 113 10051... 

Tautomers and electronic states of jet-cooled 2-aminopurine investigated by double resonance spectroscopy and theory. Phys Chem Chem Phys 7 3021-3026... 

The photodissociation dynamics of jet-cooled methyl radical produced in a pyrolysis radical beam have been investigated at 193.3 nm using photofragment translational spectroscopy by North and co-workers.112 Only... 

The photodissociation of jet-cooled methyl from a flash pyrolysis source has also been studied at 216.3 nm using the hign-n Rydberg atom time-of-flight technique by Wilson and co-workers.113 The H-atom time-of-flight spectrum indicates that predissociation of Cl l s(/)2 ) at 216.3 nm predom-... 

Koplitz and co-workers have studied the photolysis of C2H5 via the A2A (3s) state by using 248-nm photolysis radiation and hot ethyl radicals generated from photolysis of ethyl halides.125,126 Chen and co-workers have investigated the photodissociation of jet-cooled ethyl (produced by flash pyrolysis of ethyl iodide and n-propylnitrite) in the region of 245-264 nm... 

Deyerl and co-workers have also studied the photodissociation of the jet-cooled allyl radical produced in a flash pyrolysis source.148,149 The allyl radical is excited near 250 nm and H-atom product is detected by... 

Hydroxymethyl (CH2OH) The hydroxymethyl (CH2OH) is a more reactive isomer of methoxy radical. The spectroscopy and photochemistry of jet-cooled CH2OH via its 3s, 3px, and 3pz Rydberg states (in... 

Figure 5 shows a collection of S j -S0 R2PI spectra near the origin. The weak bands at low frequency are pure torsional transitions. We can extract the barrier height and the absolute phase of the torsional potential in S, from the frequencies and intensities of these bands. The bands labeled m7, wIq+, and are forbidden in the sense that they do not preserve torsional symmetry. In the usual approximation that the electronic transition dipole moment is independent of torsion-vibrational coordinates, band intensities are proportional to an electronic factor times a torsion-vibrational overlap factor (Franck-Condon factor). These forbidden bands have Franck-Condon factors m m") 2 that are zero by symmetry. Nevertheless, they are easily observed in jet-cooled spectra. They are comparably intense in many spectra, about 1-5% of the intensity of the allowed origin band. 

Figure 2. Extraction of anharmonicity constants ojexe from the comparison of fundamental OH stretching spectra (center) with overtone spectra (top) and OD spectra (bottom) for the case of jet cooled trifluoroethanol (M) and its most stable dimer conformation, which features a hydrogen bond donor stretching band (Dd) and an acceptor stretching band (Da). The deuteration analysis yields slightly different constants than the overtone approach and underestimates the hydrogen bond effect on donor stretching modes [89].

K. Le Barbu Debus, N. Seurre, F. Lahmani, and A. Zehnacker Rentien, Formation of hydrogen bonded bridges in jet cooled complexes of a chiral chromophore as studied by IR/UV double resonance spectroscopy. 2 Naphthyl 1 ethanol/(methanol)n j 2 complexes. Phys. Chem. Chem. Phys. 4, 4866 4876 (2002). 

C. Emmeluth, V. Dyczmons, and M. A. Suhm, Tuning the hydrogen bond donor/acceptor isomerism in jet cooled mixed dimers of aliphatic alcohols. J. Phys. Chem. A 110, 2906 2915... 

K. Le Barbu Debus, F. Lahmani, A. Zehnacker Rentien, N. Guchhait, S. S. Panja, and T. Chakraborty, Fluorescence spectroscopy of jet cooled chiral (+/ ) indan 1 ol and its cluster with (+/ ) methyl and ethyl lactate. J. Chem. Phys. 125, 174305 (2006). 

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