Rovibronic Infrared Spectrum of a Rigid Diatomic Rotor
 The mathematical expressions for the simulated spectra assume that the diatomic molecule is a rigid rotator, with a small anharmonicity constant (  , zero electronic angular momentum ( ), and that the rotational constants of the upper and lower states in any given transition are essentially equal ( ). It is also assumed that only the  vibrational state is thermally populated, in order to eliminate the presence of "hot bands" and simplify the spectra.The first parameter control lets you vary the fundamental vibrational frequency, which will change the spectrum position along the  axis. The second control manipulates the rotational constant  , which increases or decreases line separation. The third control manipulates temperature, and consequently the number of lines observed and their intensities. The last parameter control manipulates the line width, allowing simulation of spectra at various resolutions.These controls should be used to change how the spectrum is viewed. Line color and background color can be chosen and filling under the line can be turned on. Enabling the peak height control allows for the height of the spectrum to be manually increased or decreased. The  axis upper and lower boundary controls function to set the range of the  axis.Snapshot 1: spectra acquired at low temperatures are greatly simplified as a result of few populated rotational energy levels Snapshot 2: spectra acquired at high temperatures have many populated rotational energy levels, resulting in more observed lines Snapshot 3: spectra acquired of diatomic molecules with a large rotational constant will have larger line separation   "Rovibronic Infrared Spectrum of a Rigid Diatomic Rotor" from The Wolfram Demonstrations Project http://demonstrations.wolfram.com/RovibronicInfraredSpectrumOfARigidDiatomicRotor/ Contributed by: Whitney R. Hess and Lisa M. Goss (Idaho State University) | ||||||||||||||
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