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Science?16 December 2011:?Vol. 334?no. 6062?pp. 1541-1545?DOI:?10.1126/science.1213986 REPORT Observing the Multiexciton State in Singlet Fission and Ensuing Ultrafast Multielectron Transfer  HYPERLINK /search?author1=Wai-Lun+Chansortspec=datesubmit=Submit Wai-Lun Chan,?  HYPERLINK /search?author1=Manuel+Liggessortspec=datesubmit=Submit Manuel Ligges,?  HYPERLINK /search?author1=Askat+Jailaubekovsortspec=datesubmit=Submit Askat Jailaubekov,?  HYPERLINK /search?author1=Loren+Kaakesortspec=datesubmit=Submit Loren Kaake,?  HYPERLINK /search?author1=Luis+Miaja-Avilasortspec=datesubmit=Submit Luis Miaja-Avila,?  HYPERLINK /search?author1=X.-Y.+Zhusortspec=datesubmit=Submit X.-Y. Zhu HYPERLINK /content/334/6062/1541.full?sid=18df222b-341c-4822-a70d-6fdcd0c89f52 \l corresp-1 *  HYPERLINK /content/334/6062/1541.full?sid=18df222b-341c-4822-a70d-6fdcd0c89f52 +Author Affiliations Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA.  HYPERLINK /content/334/6062/1541.full?sid=18df222b-341c-4822-a70d-6fdcd0c89f52 \l xref-corresp-1-1 ?*To whom correspondence should be addressed. E-mail:? HYPERLINK mailto:zhu@ zhu@ ABSTRACT Multiple exciton generation (MEG) refers to the creation of two or more electron-hole pairs from the absorption of one photon. Although MEG holds great promise, it has proven challenging to implement, and questions remain about the underlying photo-physical dynamics in nanocrystalline as well as molecular media. Using the model system of pentacene/fullerene bilayers and femtosecond nonlinear spectroscopies, we directly observed the multiexciton (ME) state ensuing from singlet fission (a molecular manifestation of MEG) in pentacene. The data suggest that the state exists in coherent superposition with the singlet populated by optical excitation. We also found that multiple electron transfer from the ME state to the fullerene occurs on a subpicosecond time scale, which is one order of magnitude faste