Thank you Peter for your answer. This makes sens.

Regards,

Philippe

Hi Philippe,

You can also check Gu's Dissertation:

Gu, Qun. Improvement of Corrections for Fluorescence Inner Filter Effects Under Non-ideal Beam Conditions Based on Effective Geometric Parameters. ProQuest, 2007.

http://gradworks.umi.com/32/74/3274607.html

It gives detailed description about fluorescence measurement technique and also introduces different cuvette geometries (Figure 1-9) (Attched). 

Figure 1-11 (attached) is also helpful for understanding fluorescence measurement.

Hope it could help.

Regards

Penghui

Hi Philippe,

I agree  with the valuable answers posted from Peter and  Penghui Li.

But please don 't use acronym when you post a question  (This acronym means "Dissolved Organic Matter") .

Start Google Scholar and NOT GOOGLE in order to see if people used  larger cuvette than 1 cm for DOM research.

Here an abstract  found in it.

Abstract

High-resolution fluorescence spectroscopy was used to characterize dissolved organic matter (DOM) in concentrated and unconcentrated water samples from a wide variety of freshwater, coastal and marine environments. Several types of fluorescent signals were observed, including humic-like, tyrosine-like, and tryptophan-like. Humic-like fluorescence consisted of two peaks, one stimulated by UV excitation (peak A) and one by visible excitation (peak C). For all samples, the positions of both excitation and emission maxima for peak C were dependent upon wavelength of observation, with a shift towards longer wavelength emission maximum at longer excitation wavelength and longer wavelength excitation maximum at longer emission wavelength. A trend was observed in the position of wavelength-independent maximum fluorescence (ExmaxEmmax) for peak C, with maximum at shorter excitation and emission wavelengths for marine samples than for freshwater samples. Mean positions of these maxima were: rivers ExmaxEmmax = 340448 nm; coastal water ExmaxEmmax = 342442 nm; marine shallow transitional ExmaxEmmax = 310423 nm; marine shallow eutrophic ExmaxEmmax = 299389 nm; and marine deep ExmaxEmmax = 340438 nm. Differences suggest that the humic material in marine surface waters is chemically different from humic material in the other environments sampled. These results explain previous conflicting reports regarding fluorescence properties of DOM from natural waters and also provide a means of distinguishing between water mass sources in the ocean.

Source :

http://www.sciencedirect.com/science/article/pii/0304420395000623

Acording to Peter's answer,

It will become clear why a 1 cm path length cuvette is practically the largest cuvette in use, and why the general trend is towards using smaller ones.

Another hint:

please download manuals of companies selling fluorescence spectrometers. Most of them are  free of charge if avaible. I send you  3 pages from Edinburgh Instruments. (ownloaded as pdf)

Page 3 shows the geometrie and the cuvette.

JRG

Hi Jean Rene.

I am not sure how this abstract is answering the question about the pathlength. 

Longer not but smaller yes. It depends a lot on your absorbance.

There are lot of cells geometry available normally, most are with smaller pathway.

Best.

Stéphane

Hi Philippe,

I sent you the abstract as info for DOM   and its fluorescence and not as answer about the pathlength.

For the pathlength, try my hint with manuals. It is worthwhile to read them.

JRG

Hi Philippe,

Think about the relationship between Absorption and path length as per Beer's law. Absorption is inversely related to path length. Increasing the size of cuvette will increase the path length but simultaneously decrease in absorption will be noticed. Because absorption is what is excitation (as the molecule absorbs energy, it gets excited) so the smaller exciting energy (higher wavelengths) may not probably be helpful in investigating emitted energy (fluorescence).  We may not be able to see the emitted energy in which we are actually interested in. However, in oceanic applications where DOM is quite low, longer path length is quite common using wave guide or other analytical means (longer path length cuvettes, say 10 cm). For fluorescence smaller cuvette size make sense, because you are just looking with high exciting energy and then investigating about the florescing molecule. Chances are that you may miss some types of molecules which may gets excited at very low exciting energy but you will certainly not miss the ones which gets excited at high energy. Hope this makes some sense. Let me know what you think!

Best,

Singh

This is totally making sens Singh. Like I said, I have been working with DOM fluorescence for a long time but only in 1 cm cuvette. Your answer support why I never saw larger cuvette size for measuring fluorescence.

Best,

Philippe