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Description:
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The ability to resolve molecules individually has many potential applications .
These include understanding the local environments of single molecules including
details of their interactions with surroundings . The ability to individually address and
manipulate the spin states is also required for spin based quantum information
processing . Although optical detection techniques , such as optically detected electron
spin resonance (ESR ) seem very powerful in these contexts , multiple molecules in the
focal volume of a diffraction limited confocal microscope spot cannot in general be
resolved individually . Here we propose to solve this problem using optically detected
ESR imaging based on the use of high field gradients .
In the present research , subwavelength single molecule imaging is demonstrated
by using the optically detected ESR technique and the optically detected electron spin
echo envelope modulation (ESEEM ) technique . Ultra fast Rabi nutation experiments
are also performed to demonstrate the feasibility of fast spin manipulations at a low
microwave power . Micrometer sized gradient coils , together with micrometer sized co -planar
microstrip transmission lines , are designed and fabricated by optical lithography in order
to produce the necessary high magnetic field gradients . These fabricated devices are
used to demonstrate this subwavelength imaging technique by imaging single electron
spins of the nitrogen -vacancy (NV ) defect in diamond . In this demonstration , multiple
NV defects , unresolved in a single focal volume of a diffraction limited microscope are
successfully resolved by the optically detected ESR techniques . Specifically , two
neighboring NV defects separated by about 170nm are resolved . Ultra Fast electron
spin nutation with an oscillation period of 1 .33ns is also achieved by the high microwave
magnetic field induced by the current flowing through the fabricated co -planar
microstrip lines .
These optically detected ESR and ESEEM techniques combined with the
micrometer sized gradient coil may find many applications , including single molecule
imaging and quantum information processing . |