The Witherite Raman spectrum and its interpretation are presented below.
Witherite sample data
|Description:||Witherite mineral sample|
|Source:||Grigore Cobălcescu Museum|
|Locality:||Alston – England|
|Owner:||Department of Geology – Alexandru Ioan Cuza University of Iasi|
Witherite sample image
Main Raman bands of Witherite
|Wavenumbers (cm-1):||1059vs, 693w, 227m|
|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|
|v4 – symmetric deformation|
|NO||NO||852*||v2 – asymmetric deformation|
|v1 – symmetric stretch|
|v3 – asymmetric stretching|
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]