TY - JOUR
T1 - Generalized 1D photopyroelectric technique for optical and thermal characterization of liquids
AU - Balderas-López, J. A.
PY - 2012/6
Y1 - 2012/6
N2 - The analytical solution for the one-dimensional heat diffusion problem for a three-layer system, in the BeerLambert model for light absorption, is used for the implementation of a photopyroelectric (PPE) methodology for thermal and optical characterization of pigments in liquid solution, even for those ones potentially harmful to the pyroelectric sensor, taking the liquid sample's thickness as the only variable. Exponential decay of the PPE amplitude followed by a constant PPE phase for solutions at low pigment concentration, and exponential decay of the PPE amplitude but a linear decrease of the PPE phase for the concentrated ones are theoretically shown, allowing measurements of the optical absorption coefficient (at the wavelength used for the analysis) and the thermal diffusivity for the liquid sample, respectively. This PPE methodology was tested by measuring the thermal diffusivity of a concentrated solution of methylene blue in distilled water and the optical absorption coefficient, at two wavelengths (658 and 785 nm), of water solutions of copper sulfate at various concentrations. These optical parameters were used for measuring the molar absorption coefficient of this last pigment in water solution at these two wavelengths. This last optical property was also measured using a commercial spectrometer, finding very good agreement with the corresponding ones using this PPE technique.
AB - The analytical solution for the one-dimensional heat diffusion problem for a three-layer system, in the BeerLambert model for light absorption, is used for the implementation of a photopyroelectric (PPE) methodology for thermal and optical characterization of pigments in liquid solution, even for those ones potentially harmful to the pyroelectric sensor, taking the liquid sample's thickness as the only variable. Exponential decay of the PPE amplitude followed by a constant PPE phase for solutions at low pigment concentration, and exponential decay of the PPE amplitude but a linear decrease of the PPE phase for the concentrated ones are theoretically shown, allowing measurements of the optical absorption coefficient (at the wavelength used for the analysis) and the thermal diffusivity for the liquid sample, respectively. This PPE methodology was tested by measuring the thermal diffusivity of a concentrated solution of methylene blue in distilled water and the optical absorption coefficient, at two wavelengths (658 and 785 nm), of water solutions of copper sulfate at various concentrations. These optical parameters were used for measuring the molar absorption coefficient of this last pigment in water solution at these two wavelengths. This last optical property was also measured using a commercial spectrometer, finding very good agreement with the corresponding ones using this PPE technique.
KW - liquids
KW - optical absorption
KW - photopyroelectric technique
KW - thermal diffusivity
UR - http://www.scopus.com/inward/record.url?scp=84862070203&partnerID=8YFLogxK
U2 - 10.1088/0957-0233/23/6/065501
DO - 10.1088/0957-0233/23/6/065501
M3 - Artículo
SN - 0957-0233
VL - 23
JO - Measurement Science and Technology
JF - Measurement Science and Technology
IS - 6
M1 - 065501
ER -