16
A. G. RYDER
4.1. Steady-State
Figure 10. Definitions of fluorescence emission parameters. (A) The wavelength of maximum intensity, max.;
(B) The QF-535 factor; and (C) The Q650/500 (Red-Green-Quotient) factor. Reproduced with permission from
Ref. [68], © 2001, Elsevier.
Three of the most common steady-state parameters used within the geological
science community for oil analysis are illustrated in Figure 10. The first and most
obvious fluorescence parameter to consider is the emission wavelength and in particular
the point of maximum emission ( max ). Hagemann & Hollerbach,
15 correlated max with
the density (g/ccm) of a series of crude oils (Figure 11). The wavelength of maximum
fluorescence emission ( max ), using a 365 ± 30 nm excitation source, was later
demonstrated to correlate with saturate and aromatic concentrations (Figure 12) for a
series of mostly Canadian crude oils.
59 Using a 380 nm LED source and a small set of
North Sea oils, it was found that the width of the emission band correlated better with
API gravity than did max .
22 However, the data set was too restricted and there was no
detailed gross compositional data available.