Chemistry Reference
In-Depth Information
(a)
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
140
160
180
10
µ
m
-150
-100
-50
0
50
100
150
X
(
µ
m)
(b)
Lower left map point
Upper right map point
PVP
Crystalline Form 1
3000
2500
2000
1500
1000
500
Raman shift (cm
-1
)
Figure 4.5.
(a) Confocal Raman microscopy map (18 × 18 points) of an amorphous
dispersion containing 30% (w/w) di
unisal in PVP, shown superimposed on an optical image
of the particle obtained with bright-
eld illumination [79]. Spectra were obtained using a
633 nm laser and the stage was moved in 10 μm increments. At each map point, a spectrum
from 200 to 4000 cm
1
was taken using 16 scans with 2 s exposure time and with the full
spectrum built using
five spectral windows, for a total map acquisition time of about 14 h.
The experiment was performed using a Horiba Jobin Yvon LabRam dispersive Raman
spectrometer equipped with an Olympus BX41 confocal microscope using a 20× objective.
In (a), a false-color band ratio plot of the band area between 3060 and 3160 cm
1
(di
unisal) divided by the area between 2845 and 3050 cm
1
(PVP) is superimposed on a
bright-
eld optical image. More intense map points indicate a higher ratio of di
unisal to
PVP. (b) Raman spectra extracted from the map points marked with rectangles in (a) are
shown in comparison with reference spectra of crystalline di
unisal Form 1 and PVP.
