Negative heat capacity for a cluster of 147 sodium atoms.
نویسندگان
چکیده
There exists a surprising theoretical prediction for a small system: its microcanonical heat capacity can become negative. An increase of energy can-under certain conditions-lead to a lower temperature. Here we present experimental evidence that a cluster containing exactly 147 sodium atoms does indeed have a negative microcanonical heat capacity near its solid to liquid transition.
منابع مشابه
Premelting and postmelting in clusters.
Caloric curves for sodium clusters with N=139 and 147 atoms show a fine structure near the solid-to-liquid transition. Neither of the two sizes exhibit surface melting. For N=139, diffusion of the surface vacancies is observed, which is not possible in the closed-shell N=147 cluster. A few kelvin above the peak in the heat capacity, N=139 is completely liquid. This is not the case for N=147. He...
متن کاملComment on " Negative Heat Capacity for a Cluster of 147 Sodium Atoms "
In a recent letter [1], Schmidt et al. analyze a region where the specific heat of a Na + 147 cluster becomes negative. In Boltzmann-Gibbs (BG) statistical mechanics the specific heat can never be negative in the canonical ensemble. However, as the authors are well aware, no such property is valid in general for the microcanonical ensemble. This is indeed the case of a variety of physical situa...
متن کاملQuantum confinement and negative heat capacity
Thermodynamics dictates that the specific heat of a system is strictly non-negative. However, in finite classical systems there are well-known theoretical and experimental cases where this rule is violated, in particular finite atomic clusters. Here, we show for the first time that negative heat capacity can also occur in finite quantum systems. The physical scenario on which this effect might ...
متن کاملSimulation of Fabrication toward High Quality Thin Films for Robotic Applications by Ionized Cluster Beam Deposition
The most commonly used method for the production of thin films is based on deposition of atoms or molecules onto a solid surface. One of the suitable method is to produce high quality metallic, semiconductor and organic thin film is Ionized cluster beam deposition (ICBD), which are used in electronic, robotic, optical, optoelectronic devices. Many important factors such as cluster size, cluster...
متن کاملSurface Debye Temperatures and Specific Heat of Nanocrystals
The present study deals with the contribution of the surface atomic layer to the specific heat of nanocrystals. In the case of small phases with comparable number of bulk and surface atoms, the variation of heat capacity with respect to that of infinitely large phase is significant. To evaluate this variation, in the framework of the classical Debye model, we introduce surface excess heat capac...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review letters
دوره 86 7 شماره
صفحات -
تاریخ انتشار 2001