Photoacoustic spectroscopy Photoacoustic spectroscopy Photoacoustic spectroscopy is the measurement of the effect of absorbed electromagnetic energy (particularly of light) on matter by means of acoustic detection. The discovery of the photoacoustic effect dates to 1880 when Alexander Graham Bell showed that thin discs emitted sound when exposed to a beam of sunlight that was rapidly interrupted with a rotating slotted disk. The absorbed energy from the light causes local heating, generating a thermal expansion which creates a pressure wave or sound. Later Bell showed that materials exposed to the non-visible portions of the solar spectrum (i.e., the infrared and the ultraviolet) can
Invisible Light Invisible Light "Invisible Light" is a song by American band Scissor Sisters, serving as the third and final single from their third studio album "Night Work". The track, which features guest vocals by actor Sir Ian McKellen, was what lead singer Jake Shears felt should have been the first single released for "Night Work", even after going with "Fire with Fire". The video for "Invisible Light" features a woman having a series of nightmares. She sees herself being dragged into the woods by a group of men, sleeping in a boat on a river, and attending her own funeral. The