Thermal effects of laser irradiation on maize seeds

Abstract

It is important to know the temperature changes in seeds that have been irradiated with laser light because this could have substantial practical and theoretical importance. Thus, the thermal effects of low intensity laser irradiation on seeds was studied, showing variation of temperature produced by laser light applied during 60 s on two maize seed genotypes, 'Toluqueño' and 'Cacahuazintle': crystalline and floury, respectively, under two different conditions: natural colour and dyed black, evaluating the temperature changes by a thermal camera. The optical absorption spectra and the non-radiative relaxation time of the seeds were obtained using photoacoustic spectroscopy. The results indicate that it is possible to produce temperature changes, detected by an infrared camera, in crystalline and floury seeds when they are irradiated with a laser beam at a 650 nm wavelength and 27.4 mW power. The highest variation of temperature in the seeds was obtained for the black-dyed condition, these variations being 5.56 and 9.28°C for crystalline and floury seeds, respectively. Among the seeds, in the dyed condition, the floury seed had the lower non-radiative relaxation time, the higher optical absorption coefficient and a lower optical penetration length at the laser wavelength (650 nm).