Size effects

Text 1C

Read text 1C and answer the questions after the text.

Memorize the following basic vocabulary and terminology to text 1C

1. quantification – определение количества;

2. fall into two categories – разделяться, распадаться;

3. moderately sized clusters and nanostructures – кластеры и наноструктуры средних размеров;

4. irregular variation of the relevant property χ(n) – беспорядочное изменение значимого свойства χ(n)

5. in terms of the size equation – выраженное в уравнении размеров;

6. scaling law – правило масштабирования;

7. nuclear adiabatic dynamics – ядерно-адиабатическая динамика;

8. novel fragmentation pattern – новая модель разделения;

9. cluster fission and Coulomb explosion – разделение на кластеры и кулоновский взрыв;

10. multicharged single clusters – многозарядный единичный кластер.

A key concept for the quantification of the unique characteristics of individual nanostructures pertains to size effects. These involve the evolution of structural, thermodynamic, electronic, energetic, spectroscopic, electromagnetic, dynamic, and chemical features of finite systems with increasing size. This concept emerged from cluster chemical physics, but is applicable to other nanostructures (e.g., nanocrystals or nanowires). Size effects fall into two categories 1) Specific size effects. These involve self-selection and existence of “magic numbers” for small and moderately sized clusters and nanostructures. An irregular variation of the relevant property χ(n) (where n is the number of constitutents), with increasing the size of the nanostructure, is manifested. 2) Smooth size effects for “large” nanostructures. In this size domain, a quantitative description was advanced for the “transition” of the physical and chemical attributes of clusters to the infinite bulk system in terms of the size equation X(n) = X(∞) + Cn^–a, where C is the constant and a (a≥ 0) is a positive exponent.

Size equations constitute scaling laws for the nuclear-electronic level structure, energetics, and dynamics, providing the quantitative basis for the description of optical and electrical response of nanostructures. Nuclear adiabatic dynamics of clusters manifests new collective excitations, (e.g., compression modes), which do not have an analog in the bulk. Finite systems exhibit novel fragmentation patterns, such as cluster fission and Coulomb explosion, which are unique for finite systems and do not have an analog in the dynamics of the corresponding bulk matter. A striking example constitutes the dynamics of Coulomb explosion of multicharged single clusters, which may also prevail in nanostructures, whose energetics is characterized by a divergent scaling size equation. (1627)

Answer the following questions:

1) What do the size effects involve? 2) What are the two categories the size effects fall into? 3) What was the quantitative description advanced for? 4) What do size equations constitute? 5) What do finite systems demonstrate?

Task 1. Explain the concept “size effect” in your own words the way you understand it.

Task 2. Look through the text again and explain concept “the quantification of the individual nanostructure characteristics”.

Task 3. Remember Latin contractions such as e.g., i.e., et. al., viz., etc and many others. Learn how to read them in Latin and give their English equivalents. Use them in your own examples.

Task 4. Write an abstract on the text. Please remember that an abstract is a secondary document telling a reader what the text is about and does not give any details. Compare and discuss you abstract with a partner.