资料下载
×
Several Aspects of High Resolu
消耗积分:2 |
格式:rar |
大小:700 |
2010-08-17
分享资料个
High-resolution imaging has been
the primary feature that attracted the
researchers’ attention to scanning
probe microscopy yet there are still
a number of outstanding questions
regarding this function of scanning
tunneling microscopes and atomic force
microscopes. Here I would like to address
a few related issues starting with AFM
imaging of alkane layers on graphite.
Normal alkanes (chemical formula
CnH2n+2) are linear molecules with a
preferential zigzag conformation of the
-CH2- groups. The terminal -CH3 groups
are slightly larger than -CH2- groups
but more mobile. At ambient conditions
the alkanes with n=18 and higher are
solid crystals (melting temperature of
C18H38 – 28°C) with the chains oriented
practically vertical to the larger faces of
the crystals. Such surface of the C36H74
crystal, which is formed of -CH3 groups,
was examined in contact mode, and the
AFM images revealed the periodical
arrangement of these groups [1]. It
has been known for a long time that
on the surface of graphite the alkane
molecules are assembled in fl at-laying
lamellar structures, in which the fully
extended molecules are oriented along
three main graphite directions, Fig.1.
This molecular order is characterized
by a number of periodicities: the 0.13nm
spacing between the neighboring carbon
atoms, the 0.25nm spacing between
the -CH2- groups along the chain in
the zigzag conformation, the 0.5nm
interchain distance inside the lamellae
and the lamellae width—the length of
the extended CnH2n+2 molecule. The
latter varies from 2.3nm for C18H38 to
49.5nm for C390H782 (the longest alkane
synthesized).
the primary feature that attracted the
researchers’ attention to scanning
probe microscopy yet there are still
a number of outstanding questions
regarding this function of scanning
tunneling microscopes and atomic force
microscopes. Here I would like to address
a few related issues starting with AFM
imaging of alkane layers on graphite.
Normal alkanes (chemical formula
CnH2n+2) are linear molecules with a
preferential zigzag conformation of the
-CH2- groups. The terminal -CH3 groups
are slightly larger than -CH2- groups
but more mobile. At ambient conditions
the alkanes with n=18 and higher are
solid crystals (melting temperature of
C18H38 – 28°C) with the chains oriented
practically vertical to the larger faces of
the crystals. Such surface of the C36H74
crystal, which is formed of -CH3 groups,
was examined in contact mode, and the
AFM images revealed the periodical
arrangement of these groups [1]. It
has been known for a long time that
on the surface of graphite the alkane
molecules are assembled in fl at-laying
lamellar structures, in which the fully
extended molecules are oriented along
three main graphite directions, Fig.1.
This molecular order is characterized
by a number of periodicities: the 0.13nm
spacing between the neighboring carbon
atoms, the 0.25nm spacing between
the -CH2- groups along the chain in
the zigzag conformation, the 0.5nm
interchain distance inside the lamellae
and the lamellae width—the length of
the extended CnH2n+2 molecule. The
latter varies from 2.3nm for C18H38 to
49.5nm for C390H782 (the longest alkane
synthesized).
声明：本文内容及配图由入驻作者撰写或者入驻合作网站授权转载。文章观点仅代表作者本人，不代表电子发烧友网立场。文章及其配图仅供工程师学习之用，如有内容侵权或者其他违规问题，请联系本站处理。 举报投诉
评论(0)
发评论
- 相关下载
- 相关文章
