Carbon dioxide vibration

Let us use the carbon dioxide molecule as an example. It should have 3N - 5 or four modes of vibration. We can represent each mode by the "direction" of the associated normal coordinate, that is, the directions in which each of the atoms move in the course of the vibration. Recall that a normal mode of vibration is the simplest motion of a system of particles, and that for a system vibrating in one mode, all the particles move in phase and at the same frequency. They reach their maximum points of displacement at the same instant, and they pass through their equilibrium positions at the same instant. If we were able to take a "freeze-frame" view of carbon dioxide vibrating purely in one of its normal modes, the directions the atoms move at the instant the particles are at their equilibrium positions would serve to describe the nature of the vibration. We could represent these directions of motion by arrows at each atom, and in fact, this is a very common way of representing molecular normal modes. 

Figure C3.3.12. The energy-transfer-probability-distribution function P(E, E ) (see figure C3.3.2 and figure C3.3.11) for two molecules, pyrazine and hexafluorobenzene, excited at 248 nm, arising from collisions with carbon dioxide molecules. Both collisions that leave the carbon dioxide bath molecule in its ground vibrationless state, OO O, and those that excite the 00 1 vibrational state (2349 cm ), have been included in computing this probability. The spikes in the distribution arise from excitation of the carbon dioxide bath 00 1 vibrational mode.

Michaels C A, Mullin A S, Park J, Chou J Z and Flynn G W 1998 The collisional deactivation of highly vibrationally excited pyrazine by a bath of carbon dioxide excitation of the infrared inactive (10°0), (02°0), and (02 0) bath vibrational modes J. Chem. Phys. 108 2744-55... 

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... 

Sharma R D and Brau C A 1967 Near-resonant vibrational energy transfer in nitrogen carbon dioxide mixtures Phys. Rev. Lett. 19 1273-5... 

Yardley J T and Moore C B 1967 Intramolecular vibration-to-vibration energy transfer in carbon dioxide J. Chem. Phys. 46 4491-5... 

A particular vibration will give an absorption peak in the IR spectrum only if the dipole moment of the molecule changes dunng the vibration Which vibration of carbon dioxide the sym metric stretch or the antisymmetric stretch is infrared active 2... 

Fig. 7-8. Types of motion of a molecule of carbon dioxide, C(>2. A. Translational motion the molecule moves from place to place. B. Rotational motion the molecule rotates about its center of mass. C. Vibrational motion the atoms move alternately toward and away from the center of mass.

Fiq. 4. Polarizability changes during the vibrations of carbon dioxide (exaggerated) (7). 

Carbon Dioxide Adsorption on Dried Polymer. Other unexpected interactions of these hydrolytic polymers have been noted previously during the measurement of infrared spectra of dried Pu(IV) polymers (like those used for diffraction studies). Vibrational bands first attributed to nitrate ion were observed in samples exposed to room air however, these bands were not present in samples prepared under nitrogen atmospheres (see Fig. 4) (6). Chemical analyses established enough carbon in the exposed samples to confirm the assignment of the extraneous bands to the carbonate functional group... 

Figure 9.22 Simple vibration modes for carbon dioxide, 0=C=0 (a) a symmetric stretching mode and (b) a scissor mode vibration...

When high-temperature products are in an equilibrium state, many of the constituent molecules dissociate thermally. For example, the rotational and vibrational modes of carbon dioxide are excited and their mohons become very intense. As the temperature is increased, the chemical bonds between the carbon and oxygen atoms are broken. This kind of bond breakage is called thermal dissociation. The dissociahon of H2O becomes evident at about 2000 K and produces H2, OH, O2, H, and O at 0.1 MPa. About 50% of H2O is dissociated at 3200 K, rising to 90% at 3700 K. The products H2, O2, and OH dissociate to H and O as the temperature is increased further. The fraction of thermally dissociated molecules is suppressed as the pressure is increased at constant temperature. 

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