Carbon monoxide vibrations

The reaction of O + C2F4 produces CF2O and CF2. Subsequently, the difluorocarbene reacts with O to give CF2O which decomposes into F2 and CO. Carbon monoxide vibrational levels up to i = 11 were observed the distribution was statistical with = 0.16. °° ... 

The dynamics of fast processes such as electron and energy transfers and vibrational and electronic deexcitations can be probed by using short-pulsed lasers. The experimental developments that have made possible the direct probing of molecular dissociation steps and other ultrafast processes in real time (in the femtosecond time range) have, in a few cases, been extended to the study of surface phenomena. For instance, two-photon photoemission has been used to study the dynamics of electrons at interfaces [ ]. Vibrational relaxation times have also been measured for a number of modes such as the 0-Fl stretching m silica and the C-0 stretching in carbon monoxide adsorbed on transition metals [ ]. Pump-probe laser experiments such as these are difficult, but the field is still in its infancy, and much is expected in this direction m the near fiitiire. 

Rosser W A Jr, Sharma R D and Gerry E T 1971 Deactivation of vibrationally excited carbon dioxide (001) by collisions with carbon monoxide J. Chem. Phys. 54 1196-205... 

Margottin-Maclou M, Doyennette L and Henry L 1971 Relaxation of vibrational energy in carbon monoxide, hydrogen chloride, carbon dioxide and nitrous oxide App/. Opt. 10 1768-80... 

In using the combination difference method to obtain vibrational parameters, cOg, etc., for two electronic states between which vibronic transitions are observed, the first step is to organize all the vibronic transition wavenumbers into a Deslandres table. An example is shown in Table 7.7 for the system of carbon monoxide. The electronic... 

Section 6.13.2 and illustrated in Figure 6.5. The possible inaccuracies of the method were made clear and it was stressed that these are reduced by obtaining term values near to the dissociation limit. Whether this can be done depends very much on the relative dispositions of the various potential curves in a particular molecule and whether electronic transitions between them are allowed. How many ground state vibrational term values can be obtained from an emission spectrum is determined by the Franck-Condon principle. If r c r" then progressions in emission are very short and few term values result but if r is very different from r", as in the A U — system of carbon monoxide discussed in Section 7.2.5.4, long progressions are observed in emission and a more accurate value of Dq can be obtained. 

Electronic excitation from atom-transfer reactions appears to be relatively uncommon, with most such reactions producing chemiluminescence from vibrationaHy excited ground states (188—191). Examples include reactions of oxygen atoms with carbon disulfide (190), acetylene (191), or methylene (190), all of which produce emission from vibrationaHy excited carbon monoxide. When such reactions are carried out at very low pressure (13 mPa (lO " torr)), energy transfer is diminished, as with molecular beam experiments, so that the distribution of vibrational and rotational energies in the products can be discerned (189). Laser emission at 5 p.m has been obtained from the reaction of methylene and oxygen initiated by flash photolysis of a mixture of SO2, 2 2 6 (1 )-... 

May A. D., Stryland J. C., Varghese G. Collisional narrowing of the vibrational Raman band of nitrogen and carbon monoxide, Can. J. Phys. 

Infrared Intensities of Metal Carbonyl Stretching Vibrations, 10, 199 Infrared and Raman Studies of w-Complexes, 1, 239 Insertion Reactions of Compounds of Metals and Metalloids, 5, 225 Insertion Reactions of Transition Metal-Carbon o-Bonded Compounds I Carbon Monoxide Insertion, 11, 88... 

Figure 7. Total internal reflection sum frequency generation (TIR-SFG) vibrational spectroscopy of high-pressure room temperature adsorption of carbon monoxide on PVP-protected Pt cube monolayers and calcined (373 K, 3h) monolayers [27], The infrared spectra demonstrate CO is adsorbed at atop sites, but is considerably red-shifted on the PVP-protected Pt cubes. After calcination, the atop frequency blueshifts to 2085 cm in good agreement with CO adsorption on Pt(l 0 0) at high coverages [28], (Reprinted from Ref [27], 2006, with permission from American Chemical Society.)...

Chou KC, Kim J, Baldelli S, Somorjai GA. 2003a. Vibrational spectroscopy of carbon monoxide, acetonitrile, and phenylalanine adsorbed on liquid vertical bar electrode interfaces by sum frequency generation. J Electroanal Chem 554 253-263. 

Korzeniewski C, Pons S, Schmidt PP, Severson MW. 1986. A theoretical analysis of the vibrational spectrum of carbon monoxide on platinum metal electrodes. J Chem Phys 85 4153-4160. 

Tian ZQ, Ren B, Mao BW. 1997. Extending surface Raman spectroscopy to transition metal surfaces for practical applications. 1. Vibrational properties of thiocyanate and carbon monoxide adsorbed on electrochemically activated platinum surfaces. J Phys Chem B 101 1338-1346. 

When we activated the catalyst system on a large scale, we were unsure of whether the reaction would proceed. The only data for the catalyst activation available to us was in situ IR (React-IR) as shown in Figure 2.3. During activation of the catalyst, a single vibration frequency (-1980 cm"1) of carbon monoxides in Mo(CO)(s became five different frequencies of carbon monoxide in the catalyst solution. This IR data provided us some relief from the risk of running the large scale reaction but did not provide any clues on the structure of the true catalyst. 

Table 21 Carbon monoxide binding constants3 and carbonyl vibrational frequencies in CH3CN at 25 °C.

Adsorption enthalpies and vibrational frequencies of small molecules adsorbed on cation sites in zeolites are often related to acidity (either Bronsted or Lewis acidity of H+ and alkali metal cations, respectively) of particular sites. It is now well accepted that the local environment of the cation (the way it is coordinated with the framework oxygen atoms) affects both, vibrational dynamics and adsorption enthalpies of adsorbed molecules. Only recently it has been demonstrated that in addition to the interaction of one end of the molecule with the cation (effect from the bottom) also the interaction of the other end of the molecule with a second cation or with the zeolite framework (effect from the top) has a substantial effect on vibrational frequencies of the adsorbed molecule [1,2]. The effect from bottom mainly reflects the coordination of the metal cation with the framework - the tighter is the cation-framework coordination the lower is the ability of that cation to bind molecules and the smaller is the effect on the vibrational frequencies of adsorbed molecules. This effect is most prominent for Li+ cations [3-6], In this contribution we focus on the discussion of the effect from top. The interaction of acetonitrile (AN) and carbon monoxide with sodium exchanged zeolites Na-A (Si/AM) andNa-FER (Si/Al= 8.5 and 27) is investigated. 

The correlation of the recorded IR spectrum with semiempirical calculations and the reversible cleavage into oxohexapentaenylidene (97) and carbon monoxide give a consistent picture for both, dione 96 and carbene 97. The spectrum of 97 correlates with scaled ab initio vibrational frequencies.123 C60 97 should be a triplet molecule. Indeed, Weltner et al.124 observed during the experiment concerning C4O T-88 another triplet ESR signal which they ascribed to T-97. 

The matrix photochemistry of 2v proved to be fairly complicated.108 The primary product of the photolysis of 2v is carbene lv, which was identified by ESR spectroscopy. Under the conditions of matrix isolation the carbene showed the expected reactivity towards molecular oxygen (formation of carbonyl oxide 7v) and carbon monoxide (formation of ketene lOv) (Scheme 22). In contrast to the oxocyclohexadienylidenes (la and derivatives) carbene lv slowly reacted with CO2 to give an a-lactone with the characteristic C=0 stretching vibration at 1896 cm-1. The latter reaction indicates that lv is — as expected — more nucleophilic than la. 

Carbon monoxide on metals forms the best-studied adsorption system in vibrational spectroscopy. The strong dipole associated with the C-O bond makes this molecule a particularly easy one to study. Moreover, the C-0 stretch frequency is very informative about the direct environment of the molecule. The metal-carbon bond, however, falling at frequencies between 300 and 500 cm1, is more difficult to measure with infrared spectroscopy. First, its detection requires special optical parts made of Csl, but even with suitable equipment the peak may be invisible because of absorption by the catalyst support. In reflection experiments on single crystal surfaces the metal-carbon peak is difficult to obtain because of the low sensitivity of RAIRS at low frequencies [12,13], EELS, on the other hand, has no difficulty in detecting the metal-carbon bond, as we shall see later on. 

Vibrational Spectroscopic Studies of Adsorbate Competition During Carbon Monoxide Adsorption on Platinum Electrodes... 

We describe as rigid-body rotation any molecular motion that leaves the centre of mass at rest, leaves the internal coordinates unaltered, but otherwise changes the positions of the atomic nuclei with respect to a reference frame. Whereas in a simple molecule, such as carbon monoxide, it is easy to visualize the two atoms vibrating about a mean position, i.e. with the bond length changing periodically, we may sometimes find it easier to see the vibration in our mind s eye if we think of one atom being stationary while the other atom moves relative to it. 

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