Biomedical Engineering Reference
In-Depth Information
6.3.4  Main Features of Thermal Desorption of Gases 
from UDD
The TDMS spectra were recorded using quadruple mass spec-
trometer in the range of mass numbers from 2 to 100 amu during
programmed heating of UDD aliquots (1-2 mg) at a rate 13°C/min
up to 1100°C in vacuum. The released gases were continuously
pumped at a rate of about 1 l/s (relative to nitrogen). In this way the
measured partial pressures of gases were proportional to desorp-
tion rates at every moment.
The obtained mass spectra (more than 100) were analyzed and
handled by means of special software to calculate the intensities
of characteristic ion fragments at different temperatures, their
temperature profiles, and the relative amounts of released species.
Identifications of the chemical composition of desorbed gases were
performed using MS library (National Institute of Standards and
Technology (NIST)).
Figure 6.3
Thermal release of the main gases from UDD of types G-1
and B-1.
A variety of species were found to be desorbed from UDD
under heating in vacuum. The TPD curves shown for some of these
species in Fig. 6.3 indicate that the processes of decomposition of
different surface groups are separated on a temperature scale. For
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