Study confirms that humans may percieve infrared light
Michele Cascella at CTCC contributes to these findings.
Ill: Colourbox, PNAS
This study resolves a long-standing question about the ability of humans to perceive near infrared radiation (IR) and identifies a mechanism driving human IR vision.
Perception of near infrared radiation by the human eye
The study reveal that humans can detect IR at wavelengths longer than 1,000 nm and perceive it as visible light, a finding that has not received a satisfactory physical explanation.
Here is shown that IR light activates photoreceptors through a nonlinear optical process. IR light also caused photoisomerization of purified pigments and a model chromophore compound. These observations are consistent with the quantum mechanical model for the energetics of two-photon activation of rhodopsin.
Thus, humans can perceive IR light via two-photon isomerization of visual pigment chromophores.
Michele says about his contribution:
In order to confirm that the process observed was due to two-photon excitation, we computed the two-photon scattering cross section combining quantum mechanics, molecular dynamics, and multi-scale modelling. We found that there is indeed non-negligible probability of two-photon absorption in the region of the IR spectrum corresponding to that identified in the experiment.
The study is published in Preceedings of the National Academy of Sciences of USA.