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Good evening,

I have once done 334nm excitation and this worked fine using Zeiss
Ultrafluar lenses, old style. However, while, according to Dr. Hoecherl,
then Senior Engineer at Zeiss in Oberkochen, being excellent in
transmission even down to the limits of the VUV, these lenses were not
chromatically "corrected" for confocal resolution. (ref. P. J. Helm, O.
Franksson, K. Carlsson, Pfluegers Arch.,429, 672 (1995))

Also, I had some very old objectives from Bausch & Lomb, which were
excellent (catadioptric and Schwarzschild design). I doubt, however, you
would have them accessible, they were exquisite pieces built in five or
six exp., only. I had them on loan from an old Professor, now retired, and
do not have the slightest idea, where they are.

But perhaps you can test a Zeiss Ultrafluar. In case of inf. corrected
lenses you would also need a suitable tube lens (was available from Zeiss
many years ago).

Best wishes,
Johannes

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>
> Good morning,
> We are interested in looking at terbium luminescence and fluorescent
> aromatic amino acids.
>
> The excitation spectrum has two peaks at 241 nm and 280 nm (the first
> is for Tb itself and the second for aromatic amino acids which belong
> to the protein coordinating the metal). Tb emission is fairly broad,
> but  ~490nm and ~545nm are the strongest.
>
> Does anyone have experience exciting in those wavelengths and what is
> required?
>
> THanks
> John Shields
> Center for Ultrastructural Research
> University of Georgia
> Athens
>


-- 
P. Johannes Helm

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