1. Materials Department and the Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA.
2. Physics Department, Materials Department, and the Material Research Laboratory, University of California, Santa Barbara, CA 93106, USA.
3. Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, USA.
4. Chemistry Department, University of California, Santa Barbara, CA 93106, USA.
5. Exxon Research and Engineering Company, Annandale, NJ 08801, USA.
6. Department of Chemical Engineering, Materials Department, and the Materials Research Laboratory, University of California, Santa Barbara, CA 93106, USA.