Re: Any discussions on Conducting AFM measurements?

"Douglas Natelson" <[EMAIL PROTECTED]> ÔÚà]¼þ
news:<[EMAIL PROTECTED]> ÖÐ׫Œ‘...

> Qing, Quan wrote:

> > Hi.

> > The moderator of sci.nanotech newsgroup suggested that it may be a

> > topic here to discuss the measurements of electron transport across

> > self assembled organics monolayers on metal surfaces with conducting

> > AFM. A lot of interesting results have been shown, i.e. Frisbie's

> > group gives quite a systematic investigation nn many aspects of this

> > kind of measurements, though the reproducibility still seems to be

> > something out of control.

> >

> > Any comments?

>

> I think Frisbie's group's work is very nice.  What makes you say that

> reproducibility is a problem?

>

>



Sorry to start another thread. My news server always returned errors when I
tried to reply. :(



Well, I am currently working in a similar experiment configuration. And I'm
afraid that although some of the i-v curves showed close characteristics,
the actual range of the current differs dramatically, which is rather
annoying because all experiment parameters are carefully adjusted to be
identical, and the environment is kept in N2 atmosphere. I'm always
frustrated by the fact that the cleaning treatment of the tip is rather
tricky, not to mention a lot of experiments showed rather wildly strange or
featureless curves.

My own experience makes me believe that if there are no error bars or
statistical diagrams along with the curves in a paper, the results should be
considered with great care.

I once discussed my troubles with Dr. Cui, who has a paper on Science in
2001, regarding the effect on i-v measurements of chemical bonding in the
contacts of metal-molecule-metal junctions. And he smiled and told me that a
selection of the curves before publishing the papers is unsatisfactorily
necessary. :(

What do you think of this kind of measurements? Any suggestions on
conducting AFM experiment setups? I'll be very grateful.  :)


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Qing, Quan
Center for Nanoscale Science and Technology
Peking University
Beijing, P.R. China