Thanks for that... Sometimes the organic compound will absorb a photon and its chemical bond will break. The tendancy to do this depends on the compound. This is the basis of colour photography. In colour film there are three different compound each of which is a molecule that will absorb light at a specific colour. One for red, one for blue and one for green, these are in different layers which are protected by dyes because they are not exact in their absorbtion. When they react they activate a silver crystal so that it can be reduced by hyrdroquinone. These molecules complex the silver crystal and pass their electron to the silver ion (Ag+) thus making it Ag metal. This activates the rest of the crystal of silver chloride. When the film is developed the compounds which are broken into two smaller molecules by the light and then by the reducing action of the hydroquinone form new bonds with a component of the developer which is white but when coupled with these colour couplers in the film they form a colour. Cyan for the red absorber, magenta for the green absorber and yellow for the blue absorber. I am not sure if the colour couplers are the same compounds as the ones that absorb the light but I think so. A silverless process has been developed where the blue absorber is split by light and immediately combines with a white compound to form a yellow dye and similarly for the other colours. All that needs doing then is to fix the film and that can be done by making the colour coupling compound part if the plastic layer and washing the absorbers out of the film with solvents. Colours in films, tansparencies, clothes, and ink-jet prints all fade by absorbing light. Usually blue light and this fades reds the fastest and results in a cyan or blue garment, transparency, or ink-jet print. Pigment paints are inorganic compounds which do not split and thus do not fade. Chris http://www.chris-image.co.uk http://www.chrisscrazyideas.co.uk http://www.chrisssoftwareshop.co.uk -----Original Message----- From: owner-photoforum@listserver.isc.rit.edu [mailto:owner-photoforum@listserver.isc.rit.edu]On Behalf Of Gregory Fraser Sent: 20 June 2002 18:09 To: List for Photo/Imaging Educators - Professionals - Students Subject: RE: "Magical thinking" This is close to a photographic topic right? > -----Original Message----- > From: Chris [mailto:nimbo@ukonline.co.uk] > > The promoted electron will usually fall back and re-emit > another photon at > the same frequency but it will be in all directions so the > intensity in the > bean direction is reduced. > Chris you said the promoted electron will USUALLY fall back. Does this mean they do not always fall back? If so, is that why things fade in sunlight? Why we must never project transparencies for fear of color shift? Greg
