Mid Infrared near field microscopy
Supervisor: Dr Ben Murdin
Major Aims:
To develop a near field
microscope working in the mid-infrared region of the spectrum, for use
in semiconductor physics and bio/medical/chemical applications
Techniques used and source
of expertise:
Mid-infrared spectroscopy
will be used in conjunction with an atomic force microscope, to develop
false colour images on a sub-micron scale while using light of wavelength
several microns.
Mid-infrared spectroscopy
is very useful in the fields of semiconductor physics and elsewhere, in
particular due to the different vibrational frequencies which different
chemical bonds produce. It enables detection of molecular species and this
is important for a broad range of applications. At present, this has only
been possible on “macroscopic” samples (such as gas samples in pollution
monitoring), because the smallest thing it is possible to detect with a
given wavelength is normally several times the size of the wavelength of
the light used. However, a new technique called near field optical microscopy
has been developed for the visible region of the spectrum, in which photons
“tunnel” out of the end of an optical fibre which has been drawn to a point
much smaller than the wavelength. This has enabled images to be taken with
resolution down to 1/100th the wavelength.
Such microscopes for the
mid-infrared region of the spectrum have not so far been developed due
to the lack of suitable laser sources in that region. Using recently available
semiconductor lasers, we would like to develop an instrument based on an
idea recently published in Nature, involving an Atomic Force Microscope,
which will give surface relief information as well as the identification
of the molecules.
The microscope will be used
specifically to investigate new quantum dot semiconductor structures, and
the ordering of polymers. New samples and applications, e.g. in biochemistry,
are likely to arise in the course of the project, which is open ended and
depends on the interest of the student.
