The photochromic reaction
of the SP was carried out upon irradiation with 365-375 nm light of UV-LED (90 mW/[cm.sup.2]).
The method for calculating the photochromic reaction
rate constant was described in a previous study .
Upon photoirradiation, photochromic compounds reversibly change not only the absorption spectra but also other physicochemical properties, such as refractive index, electrical moment dielectric constants, chelate formation, ion dissociation, oxidation/reduction potentials, and phase transitions during the photochromic reaction
. Fulgides, a kind of photochromic systems, which have attracted extent interesting and lots of papers, are reported on synthesis, properties, and potential photoelectronic applications (10), (11) because of the fatigue resistance and thermally irreversibility.
(a) The photochromic reaction is temperature dependent, with the lens going darker in cold temperatures
(b) The photochromic reaction may be enhanced by an MAR coating on the lens
Writing is easily accomplished by exposing a photochromic material to focused spots of light appropriate to induce the photochromic reaction that changes the colour of the compounds at the storage site.
Unfortunately, these are the same absorptions that trigger the photochromic reactions, and sampling in these spectral regions will inevitably cause partial switching of the photochrome.
The principle behind the photochromic reaction
is a switching activity at the molecular level where the molecular structure changes photochemically and the reaction is reversible.
By monitoring the nuclear motions triggered by a specific laser pulse, it is possible to describe a realistic photochromic reaction
path and provide complementary information for the clarification of the complex mechanisms of photochromic process of SP.
Thus the observed photochromic reaction
mechanism in the present MPDMAPP doped PVA leads to the changes of chemical bond or the motion of molecular segments within the polymer matrix.
Yokoyama, "Laser multiphoton-gated photochromic reaction
of a fulgide derivative," Journal of Physical Chemistry C, vol.
This suppresses the photochromic reaction
transforming the open form to closed form, and, as a result, the average lifetime becomes longer and TPI occurs more readily.