Infrared photodissociation spectra

Buck U, Gu X, Lauenstein C and Rudolph A 1988 Infrared photodissociation spectra of size-selected (CHjGH) clusters from / = 2 to 8 J. Phys. Chem. 92 5561... 

These and more complex clusters [aniline/(H20) ]+, n = 1-8 are investigated by infrared photodissociation spectra supplemented by density functional theory calculations196. Scheme 22 gives the calculated geometries in the case of n = 4. 

The N—H N hydrogen bond is responsible for the formation of the complexes between aniline and aliphatic amines (ammonia, methylamine, dimethylamine and tri-methylamine) which act as proton acceptors. Infrared photodissociation spectra and DFT calculation indicate208 that the clusters [aniline/ammonia]+ and [aniline/methylamine]+ have a non proton transferred (without the proton donation from the aniline moiety to the amine molecule) structure, while the complexes [aniline/dimethylamine]+, [aniline/ trimethylamine]+ possess a proton transferred structure. Reasonably, the proton transfer increases on increasing the proton affinity of the amine used as solvent. 

The Infrared Photodissociation Spectra and the Internal Mobility of SF6-, SiF4-... 

THE INFRARED PHOTODISSOCIATION SPECTRA AND THE INTERNAL MOBILITY OF SFg-, SiF4- AND SiH4-DIMERS... 

Dopfer et al. recorded the infrared photodissociation spectrum of the T-shaped complex CH3CNH+-H2 and supplemented their study with MP2 calculations. The AIM charges showed that the centre of charge was close to the nitrogen-bound carbon atom. 

Figure 11. Infrared resonance enhanced photodissociation spectrum of V (OCO)5 obtained by monitoring loss of CO2. The antisymmetric stretch of outer-shell CO2 is near 2349 cm (the value in free CO2, indicated by the dashed vertical line). The vibration shifts to 2375 cm for inner-shell CO2.

Fig. 1 Infrared photodissociation action spectra in the fingerprint infrared region Irom fairly early in the modem evolution of spectroscopy of biologically interesting complex ions. These spectra illustrate the use of electrospray ion production, ion trapping mass spectrometry (Fourier-transform ion cyclotron resonance in these examples) and the FELIX free electron laser light source. Lower spectrum originally derived from [10, 11] middle spectrum frran [12] upper spectrum from [13]. Figure reproduced with permission from [12]...

This interpretation of the microwave spectrum stimulated a flurry of activity to unearth the correct equilibrium geometry. It was suggested, for example, that photoelectron spectroscopy was not inconsistent with a cyclic structure whereas iirfrared photodissociation and matrix infrared measurements suggested the two molecules are not equivalent and supported the microwave equilibrium geometry. Another set of measurements led to the notion that a tunneling motion, similar to that in the HE dimer, which interchanges the roles of proton donor and acceptor, was responsible for the two IR bands observed in the gas phase. State selection in a hexapole electric field indicated that the dimer has a small dipole moment and that it is not a symmetric top structure. ... 

The working temperature of tungsten-filament incandescent lamps lies between 2200 and 3000 K. Therefore, they emit light mostly in the visible and infrared parts of the spectrum. Such a source of radiation may be useful in photoreactions of coloured chromophores, for example in the photodissociation of bromine or chlorine molecules to initiate photohalogenation reactions (Section 6.6.1). 

Radical cations of saturated hydrocarbons have strong electronic absorptions in the visible and near-infrared region of the spectrum. The strongly colored nature of alkane radical cations is in striking contrast to neutral alkanes that absorb electronically only in the vacuum UV. The electronic absorption of alkane radical cations has been studied in the solid phase by matrix isolation using y-irradiation [1-3] and in the gas phase by ion cyclotron resonance (ICR) photodissociation in either the steady-state or pulsed mode of operation [4]. Both methods have their specific merits and drawbacks. A major concern in matrix isolation spectroscopy is spectral purity (because of the possible presence of other absorbing species) and... 

H2O, the spectrum can be identified and a few transitions are indicated. The lower trace shows the enhanced formation of OH as a function of the infrared laser wavelength, with the OH probe laser tuned to the Ri(0) transition. The comparison of the upper and the lower trace reveals that there is enhanced OH formation whenever the infrared laser excites a particular rotational transition from (0,0,0) to (0,0,1). The signals in the lower trace are due to the photodissociation of H2O from single rotational states ... 

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