Thermal and spectral response characterisation of solid samples using photothermal technique
In this study, a polyvinylidene difluoride (PVDF) film was used as a pyroelectric detector in the lateral distance scanning technique to determine the thermal diffusivity of solid samples. The samples of interest were aluminuim, copper and spray paint. The values were very close to the values obt...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English |
| Published: |
2001
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/9247/1/FSAS_2001_21.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | In this study, a polyvinylidene difluoride (PVDF) film was used as a pyroelectric
detector in the lateral distance scanning technique to determine the thermal diffusivity of
solid samples. The samples of interest were aluminuim, copper and spray paint. The
values were very close to the values obtained by previous works.
Next, the open photoacoustic cell (Ope) technique was used for measuring
thermal diffusivity of ferrite samples. The values obtained were in the range of 0.3 cm2s-
1 to 0.5 cm2s-1. EDAX analysis proved that zinc loss happened when the sample was
sintered at high temperature and the loss was accompanied by sample shrinkage and
density increment. Thus, the thermal diffusivity value increased with the amount of zinc
loss during the sintering process. A photopyroelectric spectroscopic (P2ES) technique was developed and applied
to solid samples such as poly-methyl methacrylate doped with methylene red (PMMAMR),
poly-methylmethacrylate doped with Rhodamine B (PMMA-RB) and plant leaves
to see the absorption and transmission spectrum range of samples. The spectra obtained
showed that they were of transmission type as predicted by Mandelis and Zver. The
sample condition, that was fls< Ls, Ip>Ls, in obtaining the spectrum agreed with
Mandelis and Zver's prediction. The trend of optical transmission spectrum fm doped
PMMA-MR suggests that it could be used as a cut off filter in the range of 525nm and
below to 400nm. The spectrum of PMMA-RB showed an absorption range between 500
to 550nm and a highly transmitted region above 600nm. The P2E spectra of leaf obtained
were in line to the leaf absorption spectrum obtained by Lima et a1. A young leaf has a
higher signal compared to a mature leaf because it is thinner and thus the optical
absorption length is longer than the mature leaf. At the saturated transmission spectral
region, the logarithmic signal of all these samples was found decreasing linearly with
square root of chopping frequency, agreeing to Rosencwaig and Gersho's prediction.
The spectrum of ferrite samples showed that the spectrum was similar to that of light
source because its optical length, Ip, was still small compared to sample thickness, Ls. |
|---|