Biomedical Engineering Reference
In-Depth Information
Fig. 10.1
Schematic representation of the pyrimidine molecule
(a)
and some halogenated pyrim-
idines
(b-d)
. These molecules are selected with the purpose of investigating the effect of the
halogenation on the pyrimidine ring as function of the halogen atom (chlorine/bromine) or atomic
site of halogenation (2/5)
Fig. 10.2
The C (1 s) XPS
spectrum of pyrimidine
Photoionisation/excitation and subsequent electron decay processes involving the
absorption of soft X-rays, h
ยค
, by the target molecule, M, can be outlined in the
following scheme:
Auger-decay
!
ionisation
!
M
C
.1s
1
/ C e
ph
M
2C
.
valence
2
/ C e
ph
C e
AE
(10.1)
h C M
excitation
!
Resonant-Auger-decay
!
M
.1s
1
=/
M
C
.
valence
1
/ C e
RAE
(10.2)
h C M
e
ph
e
AE
e
RAE
where
represent the photoelectron, the Auger and Resonant
Auger electrons, respectively.
The inner shell ionisation of pyrimidine has been recently studied by X-ray
photoemission spectroscopy (XPS) [
6
], showing significant chemical shifts of about
1 and 1.4 eV among the three non-equivalent carbon atoms, see Fig.
10.2
.
,
and
