powdered sample was dispersed at room temperature in a 1-cm diameter CsI pellet.
The total weight of the CsI pellet was ca. 100 mg.
Figure 5.6 shows the FTIR spectra of the powdered sample. The absorption band
at 3448 cm
À1 indicates the stretching and bending modes of OH
À in H 2 O. The
distinct absorption band at 2932 cm
À1 indicates the presence of C–H alkynes and
alkenes. Absorption bands observed at 1077 cm
À1 , 835 cm
À1 , and 581 cm
À1
indicate Al(Si)–O stretching, hydroxyl group bending, and octahedral group vibration, respectively. The broad band at 1422 cm
À1 indicates C–H bending and
stretching of methyl groups. The strong peak at 1620 cm
À1 suggests conjugated
carboxyl C¼O groups. The additional band at around 1271 cm
À1 was assigned to the
ν3 mode of CO 3
2À or a carboxyl C À O group.
5.8
27
Al Magic-Angle Spinning Nuclear Magnetic
Resonance Spectra
To examine the oxidation state of aluminum in the sclerotia grains, the
27 Al magicangle spinning (MAS) NMR spectrum was measured at 78.2 MHz using a spectrometer (DSX-300, Bruker, Billerica, MA, USA). The spinning frequency was
12 kHz and the repetition time was 2 s. Chemical shift values were recorded using
Al(H 2 O) 6
3+ as the external standard.
The
27 Al MAS NMR spectrum for sclerotia (Fig. 5.7) showed two distinct peaks
at 11.6 and 53.3 ppm, corresponding to 6-coordinated and 4-coordinated aluminum,
Fig. 5.6 Infrared spectra of sclerotia samples from the Mt. Myoko 3A horizon
84
B. Oyuntsetseg et al.