Magnetically-oscillated probe microscope for operation in liquids
First Claim
1. A scanning probe microscope for generating a signal corresponding to the surface characteristics of a scanned sample surface, said microscope comprising:
- a force sensing probe tip disposed on a first side of a free end of a flexible cantilever and adapted to be brought into close proximity to the sample surface;
a film including a magnetized material disposed on said flexible cantilever;
an XY scanner for generating relative scanning movement between said force sensing probe tip and the sample surface;
a Z control for adjusting the distance between said force sensing probe tip and the sample surface;
a deflection detector for generating a deflection signal indicative of deflection of said flexible cantilever;
an AC signal source; and
a magnetic field generator for generating a magnetic field directed toward said second side of said flexible cantilever, said magnetic field generator coupled to said AC signal source so as to modulate said magnetic field with said AC signal and cause oscillatory movement of said probe tip, said magnetic field generator including a ferrite core solenoid.
5 Assignments
0 Petitions
Accused Products
Abstract
In accordance with a first aspect of the present invention, the sensitivity of a magnetically modulated AC-AFM is substantially improved by the use of a ferrite-core solenoid for modulating the magnetic cantilever of the ACAFM. In accordance with a second aspect of the present invention, the detection system for a magnetically modulated AC-AFM incorporates AC coupling of the signal from the position sensitive detector/beam deflection detector in order to remove the DC component of the signal, resulting in significantly improved dynamic range over systems utilizing DC coupling. High frequency modulation signals are detected through the use of fast analog multipliers which, after active filtering, give a low frequency signal which may be processed by digital electronics. In accordance with a third aspect of the present invention, operation of the microscope at small amplitudes of oscillation leaves small asperities on the tip intact and results in dramatic improvement in resolution.
171 Citations
18 Claims
-
1. A scanning probe microscope for generating a signal corresponding to the surface characteristics of a scanned sample surface, said microscope comprising:
-
a force sensing probe tip disposed on a first side of a free end of a flexible cantilever and adapted to be brought into close proximity to the sample surface; a film including a magnetized material disposed on said flexible cantilever; an XY scanner for generating relative scanning movement between said force sensing probe tip and the sample surface; a Z control for adjusting the distance between said force sensing probe tip and the sample surface; a deflection detector for generating a deflection signal indicative of deflection of said flexible cantilever; an AC signal source; and a magnetic field generator for generating a magnetic field directed toward said second side of said flexible cantilever, said magnetic field generator coupled to said AC signal source so as to modulate said magnetic field with said AC signal and cause oscillatory movement of said probe tip, said magnetic field generator including a ferrite core solenoid. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A scanning probe microscope for generating a signal corresponding to the surface characteristics of a scanned sample surface, said microscope comprising:
-
a force sensing probe tip disposed on a first side of a free end of a flexible cantilever and adapted to be brought into close proximity to the sample surface; a film including a magnetized material disposed on said flexible cantilever; an XY scanner for generating relative scanning movement between said force sensing probe tip and the sample surface; a Z control for adjusting the distance between said force sensing probe tip and the sample surface; a deflection detector for generating a deflection signal indicative of deflection of said flexible cantilever; an AC signal source; a magnetic field generator for generating a magnetic field directed toward said second side of said flexible cantilever, said magnetic field generator coupled to said AC signal source so as to modulate said magnetic field with said AC signal and cause oscillatory movement of said probe tip, said magnetic field generator including a ferrite core solenoid; and a synchronous detector having said AC signal as a reference input and said deflection signal as a signal input, an output of said synchronous detector corresponding to the surface characteristics of the scanned sample surface. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A method of operating an AC-AFM, said method comprising the steps of:
-
providing a relative scanning movement between an atomic force microscope probe tip and a sample surface; magnetically driving the probe tip into oscillation; and limiting the amplitude of the oscillation of the probe tip to amplitudes not exceeding 10 nm so as to prevent damage to asperities on the probe tip.
-
Specification