Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.

(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)

4He adsorption to fullerenes

Winfried Teizer, University of Massachusetts Amherst

Abstract

Since the discovery and purification of C$\sb{60}$ there has been intense research interest in fullerenes. We are exploring the adsorption behavior of $\sp4$He on fullerenes and the possibility that several of the newly discovered carbon materials provide a host environment for $\sp4$He in which the $\sp4$He properties are substantially different from the three-dimensional case. The deeper interest in this question lies in the possibility of realizing a quantum fluid in such an environment.^ We are examining the possibilities of $\sp4$He intercalation into C$\sb{60}$ and into bundles of Single Wall Carbon Nanotubes (SWCNs). The former provides a cubic lattice with potential intercalation into the interstitial sites. The results presented here argue that deep penetration into the C$\sb{60}$ matrix does not occur under the conditions of this study. We do however find evidence for some excess adsorption that is independent of the C$\sb{60}$ film thickness. SWCNs might allow $\sp4$He intercalation into the insides of the tubes (if the endcaps are removed) or in between the tubes (if they are arranged parallel to each other), thus allowing for quasi one-dimensional systems of $\sp4$He. The results presented here show that $\sp4$He atoms are strongly bound to SWCNs with substantial $\sp4$He presence in the vicinity of the SWCNs for T $\sim$ 15K. A model of a 1-dimensional ideal gas with a binding energy of $\sim$330K is consistent with the low temperature data presented here.^ Our experiments on $\sp4$He with C$\sb{60}$ films utilize Quartz Crystal Microbalances (QCMs) that were coated with C$\sb{60}.$ We measured the $\sp4$He mass adsorption as $\sp4$He was added under isothermal conditions or under conditions where the $\sp4$He charge in the sample cell was held constant as the temperature was varied.^ The experiments of $\sp4$He in the vicinity of SWCNs use bundles of SWCNs that were stored in vacuum since purification. We measured the $\sp4$He desorption as the temperature was linearly increased from T = 14K to T = 320K. ^

Subject Area

Condensed matter physics

Recommended Citation

Teizer, Winfried, "4He adsorption to fullerenes" (1998). Doctoral Dissertations Available from Proquest. AAI9909227.
http://scholarworks.umass.edu/dissertations/AAI9909227

Share

COinS