I've been reading a book about algae, several places it mentions
fluorescence from the accessory pigments.

what would be required to see this fluorescence? I have a microscope,
and believe I could get somewhat narrow band light using a light
source and a prism.

Hi,

"Charles" wrote in message
...
I've been reading a book about algae, several places it mentions
fluorescence from the accessory pigments.

what would be required to see this fluorescence? I have a microscope,
and believe I could get somewhat narrow band light using a light
source and a prism.

Fluorescence generally means that the item absorbs a high energy photon and
emits a lower energy photon rapidly. Usually in common applications this
means you shine a black light (UV-ultraviolet) on it and it emits a visible
photon. The black lights are generally mercury vapor lamps which emit
several very sharp lines, no need for a prism, a long wave at I think around
350 nm, and a short wave around 254nm (quite damaging to the eye). Google
on black light and you will find lots of suppliers for many hobby
applications. The two lines excite different fluorescence. The short wave
is generally not transmitted through normal glass, the light bulb is quartz.
You would probably illuminate the sample without any intermediate plain
glass lens and then could look at the fluorescing visible photons normally
through the microscope. You would arrange the lighting so you are not
staring at the UV light with either eye,and the microscope optics would not
let the most dangerous UV get to your eye.
Hope that helps,
Rick

Hi Charles,

Many of the pigments in plants and algae fluoresce. In particular -
chlorophyll. As a test for water quality, chloropyll fluorescence is
used to detect certain parameters. (Chlorophyll fluorescence detected,
must mean there is algae in the water). To see the fluorescence you
need to excite the pigment with the correct frequency of light. In
most cases, the amount of fluorescence is not easily detected by the
unaided eye. Instruments made to detect the fluorescence utilize photo
diodes, avalanche diodes and photo multiplyer devices (for extreme low
level detection). You can however use a filter set to allow the
fluoresced light frequence pass through while blocking other
frequencies thus enabling you to "see" it. You are probably most
familiar with UV or black light being the excitation source at
non-visable wavelengths and then seeing the fluoresced result at
visible wavelengths. Chlorophyll is excited by light in the visible
spectrum as well as many other pigments. You can look up the
excitation frequencies of these compounds and see for yourself. Many
may have a number of excitation wavelengths, some stronger than others.
I hope this is of help.

Larry T.

Charles wrote:
I've been reading a book about algae, several places it mentions
fluorescence from the accessory pigments.

what would be required to see this fluorescence? I have a microscope,
and believe I could get somewhat narrow band light using a light
source and a prism.

UV fluorescence I am familiar with, what I was thinking at the time
was picking up some from pigments that absorb in the visual spectrum.
Things like carotenoids and phycobilins.

It may be that the fluorescence is too weak to see with home apparatus
and only absorption would be measurable. Just wondering.

Thanks

In a fluorescence microscope with near UV excitation (pretty standard
in labs) whatever thing with chloroplasts fluoresces deep red. For DIY
you will need at least a very strong lamp (a slide projector will do)
and suitable filters: the exciter, more or less near UV, and a blocking
filter that makes sure you block the UV and all remnant deep blue. And
at the same time let's through as much as possible of the longer
wavelength. UV-leds are another promising possibility, but I haven't
experimented with it.
Make sure you give it at least 10 min in a fully darkened room before
you give up: the efficiency is low and you need time to adapt to the
low light.

Rene.