摘要:

We present a novel scanning proximal probe microscope design utilizing a piezoelectric driven coarse positioning mechanism inx,y, andz, while maintaining relatively small lateral dimensions. The instrument is suitable for insertion into a Dewar. The primary purpose of this work is to develop a stable yet versatile instrument in order to meet the signal averaging limitations imposed by low signal level measurements. We have implemented a near field scanning optical microscope with this system, whose key features include simultaneous detection of reflected and transmitted signals, unique “center of mass” tip oscillator for shear force feedback, and overall microscope stability. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147988

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The tube scanner is a key part of the photon scanning tunneling microscope (PSTM). The sensitivity, resolution, scanning range and the linearity of PSTM are quite relevant to the study of the tube scanner. In this article, a new experimental method to measure the deflection sensitivity of the PZT tube is reported. The tube travel range, its linearity, and the coupling betweenxoryandzdirection are analyzed. The theoretical formula for the coupling effects are also derived. With careful design the tube scanner coupling can be neglected and the experimental results show that the linearity of the large travel tube is satisfactory. Some images of PSTM demonstrate convincingly the system performance. The imaging of Langmuir–Blodgett (LB) films and fish scale plates is a significant application of PSTM in the fields of organic materials and living specimens. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147989

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We introduce an improved piezoelectric shear-force feedback system for tip-sample distance control in a scanning near-field optical microscope. A tapered glass fiber is glued into a metal tube and both are integrated in a mounting, sandwiched between two piezosegments. One of the piezoelements excites the fiber tip at mechanical resonance while the other one is used for detection. During surface approach the fiber resonance is damped by shear forces, which is registered by the second piezoelement and used for distance control. The main attractions of this setup are its simplicity, its compactness, and the lack of disturbing light sources. The fiber is easy accessible and tip exchange is simple. With an acceptable fiber amplitude of 5–10 nm (peak to peak) we obtained a topographical resolution of 5pm/Hz. The geometry also allows the measurement of samples covered with a few millimeters of liquid, which is important for applications in biology and medicine. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147990

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In a scanning force microscopy (SFM, or atomic force microscopy) system, a simultaneous recording of the probe cantilever deflection and the corresponding probe-sample distance yields a so-called force-distance curve. When the SFM probe is away from the sample surface, there is no significant interaction between the probe and the sample and hence the deflection angle is constant. This results in a zero force change in the force-distance curve. However, in SFM probe-scanning geometry as opposed to sample scanning, a nonzero force change in a force-distance curve before probe-sample contact is usually observed. This article discusses the reasons for this phenomenon and its implications for contact mode SFM imaging and complementary measurements. It is found that such a slope is directly related to the minimum probe-sample contact force and the force uniformity that the microscope can achieve during contact imaging. Possible solutions, including a “variable set-point” scheme, are proposed. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147991

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A scanning force microscope designed for an operation at temperatures between 4.2 and 300 K is presented. The deflection of the microfabricated force sensing cantilever is detected via an optical fiber interferometer. For low temperature imaging the whole instrument is incorporated into a bath cryostat which is suitable for both liquid helium and liquid nitrogen cooling. The instrument is of highly symmetric design in order to avoid large inner misalignment of the interferometer due to thermal expansion/contraction during temperature changes. In addition to this thermally compensated design, the interferometer can be adjusted by piezo actuatorsin situin three dimensions. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147992

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A newly developed positioning system incorporating a multidegree of freedom standing wave ultrasonic motor (SWUM) is presented and its advantageous features, operating principles, and some experimental results are described. The principle of motorization is based on the conversion, through frictional contact, of a stationary bending vibration sustained in a slotted metallic resonator, into rigid body displacements. A small autonomous multidegree of freedom nanopositioner using a SWUM motor is presented for fine positioning in scanning tunneling microscopy. The positioning system is achieved via the simultaneous operation of two identical pulse width modulation servo-control systems, each having a laser vibrometer position feedback loop. The closed loop position schemes are theoretically considered and their results are demonstrated and evaluated in practice. Evaluations of experimental tests indicate that a positioning resolution less than 100 nm are successfully achieved for an unlimitedX−Ytravel range with linear speeds between1 mm s−1and fewcm s−1.©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147966

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

An x-ray projection microscope equipped with a digital camera allows a rapid and independent mapping of copper and iron ions in an aqueous sulphate solution during the corrosion/deposition process of a metallic iron electrode in a copper sulphate solution. The concentration distributions of the two species can be quantified from a pair of x-ray images acquired in 20 s with a resolution on the order of10 &mgr;m. Four pairs of images have been acquired each minute of the corrosion deposition process. This technique makes it possible to follow the concentration distribution of the two species as a function of the space(x,y)and time coordinates with a detection limit in the 10 ppm range. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147993

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have built an apparatus to study the viscoelastic response and measure the complex shear moduli of Langmuir monolayers as functions of the frequency and amplitude of the applied sinusoidal shear strain. A rotor is placed in contact with the monolayer and suspended by a torsion wire; a coil attached to the rotor carries a direct current. The voltage induced in this coil by a high-frequency external magnetic field is used to measure the angle of rotation with an accuracy of ∼0.005°. A low-frequency external magnetic field is used to drive the rotor into forced oscillations at the desired frequency (1 mHz–1 Hz), or the rotor may oscillate freely with the “natural” frequency variable over the range 0.01–3 Hz using a static external magnetic field. The apparatus has a large dynamic range for shear modulus measurement (∼5×10−3–103dyn/cm), achieved by using the free oscillation (ring-down) method for films with low shear moduli (∼5×10−3–1 dyn/cm), and the forced oscillation method for films with higher shear moduli (∼1–103dyn/cm). We have found that the complex shear modulusGof heneicosanoic acid Langmuir monolayers depends on the applied strain except at very low amplitudes. We also present sample data showing the frequency dependence ofG. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147994

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We describe a cell to study the effect of isotropic in-plane stresses on the properties of thin films: the working principle is the uniform inflation of the substrate of the film with a pressurized fluid. In order to investigate inverse magnetoelastic effects on thin ferromagnetic films, a setup composed of the cell and a magneto-optical ellipsometer is also described. Preliminary results onto electroplated Ni film are shown. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147995

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The apparatus described in this work is a novel tool which improves the capabilities of studying the static and dynamic features of wetting. It is composed, on the one hand, of an operational part which includes the mechanical setup for the precise deposition of drops and their correct viewing once they start evolving on a substrate. On the other hand, a specific vision system completes the instrument and is made up of different cameras and focusing optics, capable of acquiring images at variable rates (up to 200 Hz) and of a data-processing card designed to provide parameters such as contact angles, interfacial tensions, and spreading kinetics. Numerous examples of the use of this apparatus are provided in order to illustrate its merits within a wide range of static and dynamic situations related to the basic properties of interfaces. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147996

出版商:AIP    

年代:1997

数据来源: AIP