Document Detail

Stabilization of Large Adsorbates by Rotational Entropy: A Time-Resolved Variable-Temperature STM Study.
MedLine Citation:
PMID:  23047526     Owner:  NLM     Status:  Publisher    
Investigating the dynamics in an adlayer of the oligopyridine derivative 2-phenyl-4,6-bis(6-(pyridine-2-yl)-4-(pyridine-4-yl)pyridine-2-yl)pyrimidine (2,4'-BTP) on Ag(111) by fast scanning tunneling microscopy (video-STM), we found that rotating 2,4'-BTP adsorbates coexist in a two-dimensional (2D) liquid phase (β-phase) in a dynamic equilibrium with static adsorbate molecules. Furthermore, exchange between an ordered phase (α-phase) and β-phase leads to fluctuations of the domain boundary on a time scale of seconds. Quantitative evaluation of the temperature-dependent equilibrium between rotating and static adsorbates, evaluated from a large number of STM images, gains insight into energetic and entropic stabilization and underlines that the rotating adsorbate molecules are stabilized by an entropy contribution, which is compatible with that derived by using statistical mechanics. The general validity of the concept of entropic stabilization of rotating admolecules, favoring rotation already at room temperature, is tested for other typical small, mid-size and large adsorbates.
Thomas Waldmann; Jens Klein; Harry E Hoster; R Jürgen Behm
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-9
Journal Detail:
Title:  Chemphyschem : a European journal of chemical physics and physical chemistry     Volume:  -     ISSN:  1439-7641     ISO Abbreviation:  Chemphyschem     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100954211     Medline TA:  Chemphyschem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Institute of Surface Chemistry and Catalysis, Ulm University, 89069 Ulm (Germany).
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