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Analyze the chloroform's point group, no. of tones, symmetry vibrations, types ir active , raman active and combination give explaination
Accepted Answer
Chloroform (CHCl3) belongs to the C3v point group. Here's a breakdown:
Point Group: C3v
Number of Atoms: 4
Degrees of Freedom: 3N = 12
Vibrational Modes: 3N - 6 = 6
Symmetry Vibrations:
| Mode | Description | IR Active | Raman Active | Combination |
|---|---|---|---|---|
| ν1 | Symmetric C-H stretch | Yes | Yes | |
| ν2 | Asymmetric C-H stretch | Yes | Yes | |
| ν3 | Symmetric C-Cl stretch | Yes | Yes | |
| ν4 | Asymmetric C-Cl stretch | Yes | Yes | |
| ν5 | C-H bending | Yes | Yes | |
| ν6 | C-Cl bending | Yes | Yes | |
Explanation:
Point Group: C3v due to the presence of a threefold rotation axis (C3) and three vertical mirror planes (σv).
IR Active: A vibration is IR active if it causes a change in the dipole moment of the molecule. All vibrations in chloroform are IR active.
Raman Active: A vibration is Raman active if it causes a change in the polarizability of the molecule. All vibrations in chloroform are Raman active.
Combination Bands: Combination bands arise from the simultaneous excitation of two or more fundamental vibrations. They can be both IR and Raman active, depending on the specific combination.
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