Table 2.
Tentative Assignment of the Raman Bands Observed in the Middle Wavenumber Region
| AGIPGLGVG hN3 | VGVPGLGVG hN4 | AGVPGLGVG hN5 | AGVPGFGAG hN6 | Tentative Assignment |
|---|---|---|---|---|
| 1700-1620 (br) | 1700-1620 (br) | 1700-1620 (br) | 1700-1620 (br) | Amide I |
| – | – | – | 1605 (s) | F1 |
| – | – | – | 1586 (m) | F2 |
| 1465 (s) | 1468 (s) | 1466 (s) | – | P, I, L, V, A |
| 1451 (s) | 1452 (s) | 1452 (s) | 1454 (s) | V, L, I |
| 1421 (s) | 1421 (s) | 1420 (s) | 1421 (s) | G, A, L, I, V, P |
| 1391 (m) | 1394 (m) | 1395 (m) | 1392 (m) | G, A, L, I, V, P |
| 1343 (s) | 1345 (s) | 1343 (s) | 1341 (s) | A, L, I, V, P |
| 1315 (s) | 1313 (s) | 1317 (s) | 1320 (s) | A, L, I |
| 1300-1240 (br) | 1300-1240 (br) | 1300-1240 (br) | 1300-1240 (br) | Amide III |
| – | – | – | 1207 (s) | F3 |
| – | – | – | 1183 (m) | |
| 1161 (m) | 1175 (m) | 1161 (m) | 1159 (m) | V, L, I, P |
| 1128 (s) | 1127 (s) | 1126 (s) | 1126 (m) | V, L, I |
| – | – | – | 1101 (m) | P |
| – | – | – | 1031 (s) | F4 |
| 1031 (m) | 1034 (m) | 1031 (m) | – | G, I, P |
| 1011 (m) | 1014 (m) | 1014 (m) | A, V | |
| – | – | – | 1004 (vs) | F5 |
| 960 (s) | 962 (s) | 960 (s) | – | V, L, I |
| 937 (s) | 938 (s) | 937 (s) | 937 (br) | A, V, L, I |
| 891 (s) | 891 (s) | 891 (s) | – | V |
| 857 (m) | 860 (m) | 856 (sh) | 851 (br) | L, P |
| 845 (m) | 840 (m) | 843 (m) | – | A, V, L, I, P |
| – | – | – | 758 (br) | P |
| 736 (br) | 735 (br) | 737 (br) | – | V, L, I, P |
| – | – | – | 621 (m) | F6 |
(vs) very strong; (s) strong; (m) medium; (br) broad Raman bands. F1 to F6 refer to the six characteristic Raman bands of phenylalanine. Amide I and amide III vibrations give rise to a broad and strong Raman band peaking at ∼1685 and 1255 cm−1, respectively.