UV FLUORESCENCE

- Ultraviolet Fluorescence -

Uses ultraviolet radiation to obtain molecular information of samples.

WHAT IS IT FOR

dating

morphology

technology

origin

composition

alteration

APPLICABLE MATERIALS

Glass

Mortar

Pigments

Stone

Glass, Pigments

UV fluorescence spectroscopy is used mainly for the characterization of stained glass: the presence of transition metal ions contained in glass indicate the type of pigment used for their production (Stuart, 2007).

Concerning wall paintings and frescoes, some pigments produce characteristic UV fluorescence spectra, which are useful for their characterization.

Stone, Mortar

Areas that have undergone soluble-salt-induced decay or biological attack favored by the presence of organic materials and high relative humidity on stone building materials, mortars and wall paintings can be detected with UV spectroscopy (Castro et al., 2010).

BRIEF DESCRIPTION

UV Fluorescence spectrum.

fast
high sensitivity
for organic, inorganic and biological materials

UV Fluorescence spectrum.

Metrics

accuracy
time
cost

Sampling

in situ

invasive

destructive

TIPS

When Raman cannot identify the sample due to its fluorescence UV is a good alternative
It can identify concentration of organic materials such as biopatinas
Less accurate than other vibrational molecule technologies such as Raman or FTIR

Advantages

Ultraviolet Fluorescence Spectroscopy is a qualitative and quantitative analytical method* that uses Ultraviolet (UV) light as a primary light source for the identification and characterization of organic, inorganic and biological species. In the field of Built Cultural Heritage the method is mostly employed to identify areas that have undergone biological attack or for pigment characterization purposes of polychrome surfaces.

Limitations

non selective
very sensitive to interferences -> expertise required for analysis

HOW DOES IT WORK?

UV Fluorescence spectroscopy uses the ultraviolet spectral region of the electromagnetic spectrum as an excitation source. When UV light hits the sample, the bonding electrons of its molecules absorb a proportion of the incident UV radiation, causing them to pass from the lowest vibrational level* of the ground electronic state to an excited electronic state of higher energy. UV Fluorescence spectroscopy measures the emitted fluorescence which can be associated with the fluorophore it was emitted from Spectral libraries and databases of fl uorescent materials are then used in order to attribute peaks to compounds*. Moreover, the linear relationship between the fl uorescence output and the sample’s concentration allows for quantitative calculations.

References

Castro, F., Falcucci, C., Pelosi, C., 2010. The wall paintings of the crypt of the medieval Church of Saint Andrew in Viterbo (Italy): technical examination and state of preservation. In: A. Ferrari ed., Proceedings of the 4th International Congress on “Science and Technology for the Safeguard of Cultural Heritage in the Mediterranean Basin”, 6-8 December 2009, Il Cairo (Egypt) Vol.II, p. 106.
Clarke, M., 1999. A new technique for the non-destructive identifi cation of organic pigments, dyes and inks in–situ on early medieval manuscripts, using 3–D fl uorescence refl ectance spectroscopy.In: 6th International Conference of the Associazione Italiana Prove Non Destruttive Monitoraggio Diagnostica on Non-Destructive Testing and Microanalysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage, Rome, 17-20 May 1999: Vol. II, pp. 1421-1436.
Genestar, C., Pons, C., 2003. Ancient covering plaster mortars from several convents and Islamic and Gothic palaces in Palma de Mallorca (Spain). Analytical characterization. Journal of Cultural Heritage 4, pp. 291–298. [online] Available at http://isiarticles.com/bundles/Article/pre/pdf/1226.pdf [Accessed 8 February 2015].
Thoury, M., Elias, M., Frigerio, J. M., Barthou, C., 2007. Non-destructive Varnish Identifi cation by Ultraviolet Fluorescence Spectroscopy. Applied Spectroscopy, Vol. 61, Issue 12, pp. 1275- 1282. [online] Available at http://www.researchgate.net/publication/5653543_Nondestructive_varnish_identifi cation_by_ultraviolet_fl uorescence_spectroscopy [Accessed 8 February 2015].
Lakowicz, J. R., 2006. Principles of Fluorescence Spectroscopy (3rd ed.). New York: Springer Science & Business Media, pp. 1, 27 & 57.
Skoog, D. A., Holler, F. J., Crouch, S. R., 2007. Principles of Instrumental Analysis (6th Edition). Andover: Thomson Brooks/Cole ed., pp. 368 & 399-422.
Stuart, B. H., 2007. Analytical Techniques in Materials Conservation. New York: John Wiley & Sons, pp. 162-163.