The Witherite Raman spectrum and its interpretation are presented below.
Witherite sample data
| Description: | Witherite mineral sample |
|---|---|
| Mineral: | Witherite |
| RAMAN ID: | RAMAN5484 |
| Ideal chemistry: | BaCO3 |
| Source: | Grigore Cobălcescu Museum |
| Locality: | Alston – England |
| Owner: | Department of Geology – Alexandru Ioan Cuza University of Iasi |
Witherite sample image
Raman spectrum of Witherite
Main Raman bands of Witherite
| Wavenumbers (cm-1): | 1059vs, 693w, 227m |
|---|
Raman parameters
| Instrument settings: | Raman spectrograph HE 532nm (Horiba Jobin-Yvon) |
|---|---|
| Spectral resolution: | 2 cm-1 |
| Conditions of measurement: | at room temperature |
Interpretation of Raman spectrum of Witherite
The characteristic Raman band due to the external vibration mode (M-CO3) at 227 cm-1 and 222 cm-1, 285 cm-1 for witherite and synthetic BaCO3, respectively, and the ν1 internal mode (symmetric stretching) for both witherite sample at 1059 cm-1 are easily distinguished. In the Raman spectrum of the witherite and synthetic BaCO3 samples don’t have values below 200 cm-1 because the spectral range is between 200-3400 cm-1.
The Raman spectra for the witherite and synthetic BaCO3 are very similar the only differences are found in the 200-300 cm-1 region. In the synthetic BaCO3 spectra appear one peak in addition at 285 cm-1 attributed to the external vibration mode. As can be seen in Raman spectra, witherite and BaCO3 synthetic do not present values below 200 cm-1 because the spectral range is between 200-3400 cm-1. The intense ν1 symmetric stretching mode of carbonate group is at 1059 cm-1 for both spectra. The bands at 1422 cm-1 and 1421 cm-1 are due to the ν3 asymmetric stretching mode, and the bands at 1511 cm-1 and 1508 cm-1 are not assigned. The ν2 vibration mode is not observed. The Raman line at 693 cm-1 is attributed to ν4 vibration.
| Buzgar and Apopei, 2009 | Buzgar and Apopei, 2009 | Krishnamurti, 1960 | Beny, 1989 | Assignment |
| sample no. 5484 | synthetic BaCO3 | |||
| 227 | 222, 285 | 227 | 224 | T(M,CO3) |
| 693 | 693 | 691 699 |
690 696 |
v4 – symmetric deformation |
| NO | NO | 852* | v2 – asymmetric deformation | |
| 1059 | 1059 | 1061 | 1035 1059 |
v1 – symmetric stretch |
| 1422 1511 |
1421 1508 |
1394 1409 1421 |
1419 1505 |
v3 – asymmetric stretching |
| NO | NO | 2116* | 2v1 |
The frequencies marked with asterisk are reported for the first time.
NO = not observed.
References for the Raman spectrum of Witherite
- BUZGAR N., APOPEI A. I. (2009) – The Raman study on certain carbonates. Analele Stiintifice ale Universitatii “Al. I. Cuza” – Iasi, Tome 55, issue 2, 97-112 [link]
- KRISHNAMURTI D. (1960) – The Raman spectra of aragonite, strontianite and witherite. Indian Academy of Sciences [link]
- BENY C. (1989) – Societe Francaise de Mineralogie et de Cristallographie – Base donnees de spectres Raman. Witherite [link]