Aragonite Raman spectra - Romanian Database of Raman Spectroscopy

Aragonite: Crystal structure | Sample photo | Raman spectrum | Interpretation | References

Crystal structure of Aragonite

Formula:	CaCO₃
Crystal Data:	Crystal System: Orthorhombic - Dipyramidal
	Point Group: 2m/2m/2m
Cell Data:	Space Group: Pmcn, a = 4.959, b = 7.968, c = 5.74, Z = 4
Using the mouse (click here for more information)	Density (calc.) = 2.930 and V = 226.85 Å³
		Element color: Ca, C, O

Aragonite sample

Sample no. 5473 from the "Mineralogy and Petrography Museum Grigore Cobălcescu" of "Alexandru Ioan Cuza" University, Iaşi.

Origin: Corund - Romania.

Click image to enlarge

Raman spectrum and vibrations of Aragonite

Interpretation of Raman spectrum of Aragonite

The characteristic Raman band due to the external vibration mode (M-CO₃) at 250 cm^-1, and the ν₁ internal mode (symmetric stretching) at 1083 cm^-1 are easily distinguished. In the Raman spectrum of the aragonite sample don't have values below 200 cm^-1 because the spectral range is between 200-3400 cm^-1.

In case of aragonite only four bands out of the 30 predicted Raman-active modes (J. Urmos et al., 1991) were detected in the Raman spectra of the aragonite sample no. 5473. This spectrum is governed by the very strong Raman line (1083 cm^-1) atributed to the ν₁ symmetric stretching mode of the carbonate group. The ν₄ mode of CO₃ has values at 701 cm^-1. The ν₂ vibration mode is not observed in this study; ν₃ vibration are observed at 1461 and 1573 cm^-1.

The frequencies of all Raman bands observed in Aragonite, Strontianite and Witherite can be corelated with the atomic masses of the cations.

Buzgar et al., 2009¹	Urmos, 1991	Krishnamurti, 1960	Assignment
250	284	285	T(Ca,CO₃)
701	701 705	702 707 716	ν₄ symmetric deformation
NO	853	854	ν₂ asymmetric deformation
1083	1085	1086	ν₁ symmetric stretch
1461 1573	1462 1547	1415 1463	ν₃ asymmetric stretching
	1547		NA
NO		2165	2ν₁

NO = not observed; NA = not assigned.

References

• The Mineralogy Database [link]

• Crystal data (.cif file) from the American Mineralogist Crystal Structure Database [link]

• ¹BUZGAR 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]

• URMOS J., SHARMA S. K., MACKENZIE F. T. (1991) - Characterization of some biogenic carbonates with Raman spectroscopy. American Mineralogist, 76, p. 641-646 [link]

• KRISHNAMURTI D. (1960) - The Raman spectra of aragonite, strontianite and witherite. Indian Academy of Sciences [link]



Element color: C, O Toggle Grid Toggle Coordinates Reverse Spectrum				Click to in the Raman spectrum. To see the vibrations click on one of them (highlight region) and it (the selected vibration) will appear on the right side of the Raman spectrum. Below spectra are various settings, and other vibrations of aragonite (which are not present in this spectrum). You have the possibility to zoom in the spectrum by selecting a spectral region you need to be increased (along axis x); to zoom keep the left mouse-click continously pressed, drag (to left or to right) and release the left button. To return to the initial size spectrum, press the right click on the spectrum -> Zoom -> Reset View.
Model type: Sticks Ball-and-Sticks (1) Ball-and-Sticks (2) CPK (Spacefill) Orientation: Reset view Front view Back view Left view Right view Top view Bottom view	Background color: Reset White(1) Black Spin on Spin off Symbols on Symbols off CO₃ polyhedra on CO₃ polyhedra off	Vibrations: 701 cm^-1 - ν_4b (E') 1083 cm^-1 - ν₁ (A'₁) 1461 cm^-1 - ν_3a (E') 1573 cm^-1 - ν_3b (E') Vibration on Vibration off	Download spectrum: Raman spectrum .txt Raman spectrum .spc Vectors on Vectors off Measure distances Delete measure Axes on Axes off

SPAFMSR

Aragonite: Crystal structure | Sample photo | Raman spectrum | Interpretation | References