Optical sensor for hydrogen bonding gaseous molecules

An optical system for obtaining a quantity of hydrogen bonding gaseous molecules, the optical system comprising

• an optically transparent matrix comprising a molecule containing a hydroxyazobenzene group embedded in the matrix;
• an isomerizing light source;
• at least one light detector for measuring absorbance changes from the optically transparent matrix;
• and
• measurement control electronics configured to control the isomerizing light source, the at least one light detector, and optionally a second light source, wherein the measurement control electronics are configured to
• control the isomerizing light source to illuminate the optically transparent matrix with isomerizing light capable of inducing trans-cis isomerization in the hydroxyazobenzene group,
• control the at least one light detector to measure absorbance changes from the optically transparent matrix at a single or multiple wavelength(s) to obtain a thermal cis-trans isomerization time constant, and
• obtain the quantity of the hydrogen bonding gaseous molecules by using a dependency of the thermal cis-trans isomerization time constant on the quantity of the hydrogen bonding gaseous molecules.