The Raman spectrum of propylene was obtained by experiment, but the measured Raman peaks were different from those described in the book "Vibrational Spectra and Structure of Polyatomic Molecules".
Could you help me with this problem？ (what are the vibration modes of these Raman peaks, such as 425, 917, 1296, 1419, 1460, 1652, 2735, 2790, 2830, 2855, 2867, 2890, 2898, 2910, 2931, 2953, 2972, 2983, 2990, 3005, 3011, 3020, 3090 cm-1 )
Can you please post you measured spectrum as well?
But just from the number of peaks you posted there is probably some impurity or maybe there's dirt in the optical path of the spectrometer. You posted 23 wavenumbers and C3H6 has only 21 vibrational degrees of freedom, some of which are Raman-inactive or degenerate as the book lists.
Yes, I calculated its vibration modes by Gaussian 09 that were 21, but it does not correspond to the actual measured value (see Fig. 1)， which is
OK, I just saw that the table you posted first was Cyclopropane, not propylene, that's also C3H6, but it's a different compound. If you look at the wavenumbers at the bottom of the table you posted now (1295, 1414 etc.) these match you measurement actually pretty decently. Maybe you can look up the original work of Mr. Burguel from Comptes Rendus on gallica.bnf.fr, more detailed explanations on the access to the volumes of that can be found in the wikipedia entry: https://en.wikipedia.org/wiki/Comptes_rendus_de_l%27Acad%C3%A9mie_des_Sciences
I recall that the archive there is a bit tricky to handle, but in the end it usually works.
The article will be in French, but all you need in the end are the wavenumbers.
Well, thanks very much for your kind help, and I'm so sorry for making a mistake in the table posted first.
As you can see, the measurement matches the wavenumbers well listed in the second posted table (column 3 in Fig. 2, published in ''the Raman spectra of propylene and iso-butane"), but the author didn't give any explanations about the peak assignment. By the way, could you tell me what that means in column 2 in Fig. 2? I couldn't fully understand this table in Fig. 2.
I read the work of Mr. Burguel by the method you provided, and he also just listed these wavenumbers without any details. Actually, maybe it's a hard job to figure out their vibration mode.
Regarding the second column: I'd say that this is the absolute wavenumber (not the Raman shift) that was observed; if you look at the letters, for all e labeled vibrations the shift plus the absolute number have the identical sum. Maybe these experiments were carried out with different excitation wavelengths and the letter specifies which it was? Does your source say anything about that?
I upload the paper (see in C3H6 (1936)), where the light source is a quartz mercury arc, you can see the information marked with the highlight. There is no detailed explanation about that.
Mercury arcs have a certain set of characteristic emissions:
http://zeiss.magnet.fsu.edu/articles/lightsources/images/mercurylampsfigure1.jpg
Probably the letters are an old indexing system for these linesthat back in the days used to be common knowledge.
- Badges
- Science topic
- Similar topics
- Physics
- Condensed Matter Physics
- Solid State Physics
- PEAKS