Re: Excitation spectrum with excitation to S2 or higher?

Posted by Alex Asanov on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Excitation-spectrum-with-excitation-to-S2-or-higher-tp7588313p7588315.html

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Hi Steffen,

Porphyrins with their S0-->S2 Soret bands stronger than S0-->S1, and vibronic bands clearly dependent on the chelated  metal and substitutes at porphyrin ring, are definitely the champions and excellent objects for your purpose, I guess. There is vast literature on fluorescence  of porphyrins. E.g. http://www1.lasalle.edu/~prushan/Abs%20and%20Fluor%20of%20TPPH2.pdf.

Best regards,
Alexander N. Asanov, Ph.D.
President,  TIRF Labs
[hidden email]
www.tirf-labs.com   www.TIRFmicroscopy.com



-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Steffen Dietzel
Sent: Tuesday, May 29, 2018 3:41 AM
To: [hidden email]
Subject: Excitation spectrum with excitation to S2 or higher?

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Dear all,

I guess all of us who are teaching fluorescence microscopy came to the
point where they mentioned excitation to S2 and higher states, and that
this shows in the excitation spectrum. I was wondering whether anybody
knows of an example where a specific higher energy state (S2, S3, S4...)
can be assigned to a specific second maximum in the excitation spectrum.

Some spectra have pretty nice local maxima, like Texas Red around 550
nm, or at least shoulders like TRITC around 520 nm. But is this S2 or S3
or even higher? The problem arises because if S2 has only a little more
energy than S1 the two peaks will not be resolvable.

So I was hoping that somebody may know of an example where the shoulder
or secondary maximum can be assigned to a specific state. Preferably of
a widely used fluorochrome, but anything is welcome. If it should come
from a citable source, even better.

Best

Steffen

--
------------------------------------------------------------
Steffen Dietzel, PD Dr. rer. nat
Ludwig-Maximilians-Universität München
Biomedical Center (BMC)
Head of the Core Facility Bioimaging

Großhaderner Straße 9
D-82152 Planegg-Martinsried
Germany

http://www.bioimaging.bmc.med.uni-muenchen.de


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