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Local Fluorescence Quenching Probe

IP.com Disclosure Number: IPCOM000109238D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 3 page(s) / 134K

Publishing Venue

IBM

Related People

Gerber, CE: AUTHOR [+4]

Abstract

Fluorescence microscopy and histochemistry involve illuminating a specimen, prepared for optical microscopy, with ultraviolet or blue light. By selecting a higher wavelength region of the spectrum using a suitable filter, the recorded image is that of a self-luminous object constituting a specific fluorescent species. The technique is widely used in chemistry, biology and pathology and in medical research since about 1940.

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Local Fluorescence Quenching Probe

       Fluorescence microscopy and histochemistry involve
illuminating a specimen, prepared for optical microscopy, with
ultraviolet or blue light.  By selecting a higher wavelength region
of the spectrum using a suitable filter, the recorded image is that
of a self-luminous object constituting a specific fluorescent
species. The technique is widely used in chemistry, biology and
pathology and in medical research since about 1940.

      A specific aspect of fluorescence occurs when an active
molecular structure is in close vicinity of a metallic or
semiconductor surface: the quenching of the fluorescence.  This
suggests that a sharp metallic or semiconductor probe in a scanning
tunneling microscope, force microscope, or variant thereof, can be
used as a local sensor to detect the proximity of the probe tip to a
fluorescent molecular species or to the substituent of a larger
structure.  There is a variety of methods for detecting the local
quenching and, hence, the actual position of the tip apex
independently of topography or other information.

      Most of the existing forms and experimental configurations for
conventional fluorescence microscopy can be adapted.  Modulation of
the distance and, thus, also of the light emitted at a point of
interest, which can be detected in the optical image or part thereof,
provides the local position of a fluorescently active species of
interest.  Photomultipliers and other detectors, spectrographs,
possibly with computer-controlled image recognition routines, can be
employed.  The fluorescent species can also be specifically bound to
the tip to provide a representation of the tip proximity to the
surface.  In this respect, the method can be used for the controlled
transfer of fluorescently labelled objects from tip to surface and
vice-versa.

      If either the tip or surface quench the fluorescence while the
other does not (i.e., glass tip and metallic surface, or glass
surface and metallic tip), then fluorescence will be detected
depending on whether the object is attached to the tip or to the
surface, given that the tip could be momentarily retr...