10.2 Reactivity of Met-Cars
167
Fig. 10.3 Mass spectra of products arising from reactions of Ti 8 C 12
+ with a H 2 O and b ND 3 .
The number indicates the number of H 2 O (or ND 3 ) associating onto Ti 8 C 12
+ . Note that association
reactions terminate at the eighth step. Reproduced with permission from Ref. [65]
also found to be terminated at the eighth step for water and ammonia system, as seen
in Fig. 10.3. They can be represented as
Ti 8 C
+
12 + 8H 2 O → Ti 8 C
+
12 (H 2 O) 8
(10.4)
Ti 8 C
+
12 + 8ND 3 → Ti 8 C
+
12 (ND 3 ) 8
(10.5)
Further researches in this area have found that the Met-Cars are not limited to
Ti 8 C 12
+ . For example, researchers have also found Nb 8 C 12
+ sharing the equivalent physics and chemistry as Ti 8 C 12
+ . Figure 10.4 shows two photoionization mass
spectra measured for vanadium/carbon and niobium/carbon cluster distributions at
215 nm. V 8 C 12
+ and Nb 8 C 12
+ appear in these mass spectra with sharp peak in resolution because both V and Nb metals have only one naturally occurring isotope,
indicating that the Met-Car clusters have reasonable abundances in the molecular
beam. Nevertheless, there might also be additional clusters with equal or greater
Fig. 10.4 Photoionization mass spectra for V 8 C 12
+ and Nb 8 C 12
+ clusters at 215 nm. Laser power
dependence studies show that these spectra are the result of multiphoton absorption of at least two
photons. Reproduced with permission from Ref. [79]. Copyright 1996 American Chemical Society