Photopyroelectric spectroscopy of polyaniline films

Determination of thermal and optical properties of ion implanted polyetheretherketone films by photothermal spectroscopies

“…The measuring system is composed of a lock-in amplifier, locked at the chopper frequency, connected to a microcomputer that stores the data and controls the experiment. The mechanical slotted wheel chopper modulates the incident light whose intensity obeys the expression [14][15][16]19,23 …”

“…The detected signal V͑ , t͒ is proportional to the pyroelectric coefficient p of the detector and to the temperature distribution along the detector thickness: 15,16,18,19,22,23 …”

“…The heat propagation across the whole chamber is governed by heat diffusion equations of each medium coupled via boundary conditions at the interfaces ͑T a = T b and exp͑± R L R ͒Ϸ1, ͉r R ͉ ӷ 1, and R Ϸ 1, where r n = ␤ n / n and n = ͑1+i͒a n , with a n = ͑f / ␣ n ͒ 1/2 ͑n = g , s , p; that is, g = gas, s = sample, and p = pyroelectric͒. Then, the normalized voltage signal results in 16,19,23,24 …”

“…[10][11][12][13] Among the PTS techniques, photoacoustic spectroscopy ͑PAS͒, 14 which is the most traditional one, and the more recent photopyroelectric spectroscopy 15 ͑PPES͒ have been used for studying thermal and optical properties of polymeric films and semiconductors. [16][17][18][19][20][21][22][23][24] In these techniques a pulsed light beam is absorbed in a solid sample and the converted heat diffuses into the bulk structure; the sample expansion, or the temperature gradient, is then detected by an appropriate sensor system. The detected signal depends on the optical and thermal properties of the sample: the optical absorption coefficient ␤͑͒ ͑ being the light wavelength͒, the nonradiative conversion efficiency ͑͒, the thermal conductivity k, and the thermal diffusivity coefficient ␣.…”

Perspective: Photopyroelectric effects and pyroelectric measurements: “Invited Review Article: Photopyroelectric calorimeter for the simultaneous thermal, optical, and structural characterization of samples over phase transitions” [Rev. Sci. Instrum. 82, 121101 (2011)]

“…36 More recently, these boundaries were further extended to the spectroscopy of ceramics, such as Sb 2 O 3 -ZnO, 37 and of polymers, such as polyaniline films. 38 Owing to its ability to measure thermal energy released from non-radiative electron-hole (or carrier-defect state) recombinations, PPES has been making a strong impact in the field of semiconductor science and technology. Mandelis et al 39 have presented PPE spectra of a Si:H thin semiconducting films on quartz.…”