Experimental plans

Clusters of C60 are held together in some way by binary solutions of methanol/water in a 50% solution.

• We shall attempt to cause their disassembly by changing the pH outside the range of stability, <4 through a laser photolysis initiated pH-jump technique. o-NBA absorbs strongly at 337nm, therefore solutions of this in C60 clusters are hypothesized to cause break-up on radiation with the nitrogen laser.

Two expts. are initially planned this term:

1. Tune the system and explore the NBS reaction. Since the lifetime of NBA is short (<6ns), we will use bromo cresol green (BCG) indicator that absorbs strongly around 600 nm as a probe of the NBA. Using a 10-micromolar BCG solution of NBA, pump with 337 and probe the transient signal (not species) at 633 with the HeNe laser.

Tune the HeNe light to be under the saturation limit of the PMT by divergent lens/neutral density filter/pinhole, etc. Observe signal on DSO.

2. Apply results to the meta-stable C60 clusters. Titrate the C60 system to a pH near 4, use photolysis of NBA without a dye indicator to initiate disassembly of the clusters. Measure the transient signal at an appropriate wavelength to catch the mauve-to-tan color expected. The lifetime of this transition is expected to be in the ms range.