Generalized Heterodyne Configurations for Photo-induced Force Microscopy

<div>Infrared chemical microscopy through mechanical probing of light-matter interactions by atomic force microscopy (AFM) bypasses the diffraction limit. One increasingly popular technique is photo-induced force microscopy (PiFM), which utilizes the mechanical heterodyne signal detection between cantilever mechanical resonant oscillations and the photo induced force from light-matter interaction. So far, photo induced force microscopy has been operated in only one heterodyne configuration. In this article, we generalize heterodyne configurations of photoinduced force microscopy by introducing two new schemes: harmonic heterodyne detection and sequential heterodyne detection. In harmonic heterodyne detection, the laser repetition rate matches integer fractions of the difference between the two mechanical resonant modes of the AFM cantilever. The high harmonic of the beating from the photothermal expansion mixes with the AFM cantilever oscillation to provide PiFM signal. In sequential heterodyne detection, the combination of the repetition rate of laser pulses and polarization modulation frequency matches the difference between two AFM mechanical modes, leading to detectable PiFM signals. These two generalized heterodyne configurations for photo induced force microscopy deliver new avenues for chemical imaging and broadband spectroscopy at ~10 nm spatial resolution. They are suitable for a wide range of heterogeneous materials across various disciplines: from structured polymer film, polaritonic boron nitride materials, to isolated bacterial peptidoglycan cell walls. The generalized heterodyne configurations introduce flexibility for the implementation of PiFM and related tapping mode AFM-IR, and provide possibilities for additional modulation channel in PiFM for targeted signal extraction with nanoscale spatial resolution.</div>

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Recent advances in AFM-based biological characterization and applications at multiple levels

Soft Matter ◽

10.1039/d0sm01106a ◽

2020 ◽

Vol 16 (39) ◽

pp. 8962-8984

Author(s):

Wenfeng Liang ◽

Haohao Shi ◽

Xieliu Yang ◽

Junhai Wang ◽

Wenguang Yang ◽

...

Keyword(s):

Atomic Force Microscopy ◽

Spatial Resolution ◽

High Spatial Resolution ◽

Natural Environments ◽

Biological Characterization ◽

Force Microscopy ◽

The Past ◽

Atomic Force ◽

Wide Range ◽

Multiple Levels

Atomic force microscopy (AFM) has found a wide range of bio-applications in the past few decades due to its ability to measure biological samples in natural environments at a high spatial resolution.

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Direct Magnetic Excitation of Cantilevers for Dynamic Force Microscocopy in Liquids

Microscopy and Microanalysis ◽

10.1017/s143192760001833x ◽

1999 ◽

Vol 5 (S2) ◽

pp. 1002-1003

Author(s):

S.M. Lindsay

Keyword(s):

Acoustic Excitation ◽

Dynamic Force ◽

Viscous Damping ◽

Driving Frequency ◽

Magnetic Excitation ◽

Force Microscopy ◽

Wide Range ◽

Recognition Imaging ◽

Afm Cantilever ◽

Body Recognition

The mechanical Q-factor of an AFM cantilever immersed in fluid is reduced to a small value (ca. 3) owing to viscous damping. Thus, a large driving force is needed to excite the cantilever into bending motion in fluid. There are two common methods for exciting cantilevers for dynamic force microscopy in fluids, illustrated in Figure 1. Fig. la illustrates acoustic excitation in which a piezoelectric transducer displaces the base of the cantilever, causing bending motion of the cantilever when the driving frequency is near to a bending resonance of the cantilever. Fig. lb shows magnetic excitation. In magnetic excitation, a magnetic field is used to cause bending of a magnetic cantilever either through magnetostriction or MXB forces.Acoustic excitation has the highest amplitude at mechanical resonances of the cantilever housing, with the result that the response is dominated by these sharp features,Fig. 2a. In contrast, the response to magnetic excitation is intrinsic to the cantilever, Fig. 2b. Thus, magnetic excitation permits the cantilever to be driven over a wide range of frequencies. This is important for calibration of the amplitude and for experiments involving time and concentration dependence in tip-sample interactions, e.g., anti-body recognition imaging.

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Comparative Effects of High-Tech Visual Scene Displays and Low-Tech Isolated Picture Symbols on Engagement From Students With Multiple Disabilities

Language Speech and Hearing Services in Schools ◽

10.1044/2019_lshss-19-0007 ◽

2019 ◽

Vol 50 (4) ◽

pp. 693-702 ◽

Cited By ~ 1

Author(s):

Christine Holyfield ◽

Sydney Brooks ◽

Allison Schluterman

Keyword(s):

Language Learning ◽

Augmentative And Alternative Communication ◽

Visual Analysis ◽

Multiple Disabilities ◽

Visual Scene ◽

Future Research ◽

High Tech ◽

Single Subject ◽

Wide Range ◽

The Difference

Purpose Augmentative and alternative communication (AAC) is an intervention approach that can promote communication and language in children with multiple disabilities who are beginning communicators. While a wide range of AAC technologies are available, little is known about the comparative effects of specific technology options. Given that engagement can be low for beginning communicators with multiple disabilities, the current study provides initial information about the comparative effects of 2 AAC technology options—high-tech visual scene displays (VSDs) and low-tech isolated picture symbols—on engagement. Method Three elementary-age beginning communicators with multiple disabilities participated. The study used a single-subject, alternating treatment design with each technology serving as a condition. Participants interacted with their school speech-language pathologists using each of the 2 technologies across 5 sessions in a block randomized order. Results According to visual analysis and nonoverlap of all pairs calculations, all 3 participants demonstrated more engagement with the high-tech VSDs than the low-tech isolated picture symbols as measured by their seconds of gaze toward each technology option. Despite the difference in engagement observed, there was no clear difference across the 2 conditions in engagement toward the communication partner or use of the AAC. Conclusions Clinicians can consider measuring engagement when evaluating AAC technology options for children with multiple disabilities and should consider evaluating high-tech VSDs as 1 technology option for them. Future research must explore the extent to which differences in engagement to particular AAC technologies result in differences in communication and language learning over time as might be expected.

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COMBINATORIAL POLYNOMIALLY COMPUTABLE CHARACTERISTICS OF SUBSTITUTIONS AND THEIR PROPERTIES

Computational nanotechnology ◽

10.33693/2313-223x-2020-7-2-34-41 ◽

2020 ◽

Vol 7 (2) ◽

pp. 34-41

Author(s):

VLADIMIR NIKONOV ◽

◽

ANTON ZOBOV ◽

Keyword(s):

Mathematical Expectation ◽

Point Of View ◽

Small Range ◽

Computational Point ◽

Wide Range ◽

Bijective Function ◽

The Difference ◽

Element Base ◽

Selection Of

The construction and selection of a suitable bijective function, that is, substitution, is now becoming an important applied task, particularly for building block encryption systems. Many articles have suggested using different approaches to determining the quality of substitution, but most of them are highly computationally complex. The solution of this problem will significantly expand the range of methods for constructing and analyzing scheme in information protection systems. The purpose of research is to find easily measurable characteristics of substitutions, allowing to evaluate their quality, and also measures of the proximity of a particular substitutions to a random one, or its distance from it. For this purpose, several characteristics were proposed in this work: difference and polynomial, and their mathematical expectation was found, as well as variance for the difference characteristic. This allows us to make a conclusion about its quality by comparing the result of calculating the characteristic for a particular substitution with the calculated mathematical expectation. From a computational point of view, the thesises of the article are of exceptional interest due to the simplicity of the algorithm for quantifying the quality of bijective function substitutions. By its nature, the operation of calculating the difference characteristic carries out a simple summation of integer terms in a fixed and small range. Such an operation, both in the modern and in the prospective element base, is embedded in the logic of a wide range of functional elements, especially when implementing computational actions in the optical range, or on other carriers related to the field of nanotechnology.

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Liquid-Phase Peak Force Infrared Microscopy

10.26434/chemrxiv.12401621.v1 ◽

2020 ◽

Author(s):

Haomin Wang ◽

Joseph M. González-Fialkowski ◽

Wenqian Li ◽

Yan Yu ◽

Xiaoji Xu

Keyword(s):

Liquid Phase ◽

Spatial Resolution ◽

Shear Force ◽

Polymer Surface ◽

Surface Damage ◽

Peak Force ◽

Infrared Microscopy ◽

Contact Mode ◽

Force Microscopy ◽

Hydrogen Deuterium

Atomic force microscopy-infrared microscopy (AFM-IR) provides a route to bypass Abbe’s diffraction limit through photothermal detections of infrared absorption. With the combination of total internal reflection, AFM-IR can operate in the aqueous phase. However, AFM-IR in contact mode suffers from surface damage from the lateral shear force between the tip and sample, and can only achieve 20~25-nm spatial resolution. Here, we develop the liquid-phase peak force infrared (LiPFIR) microscopy that avoids the detrimental shear force and delivers an 8-nm spatial resolution. The non-destructiveness of the LiPFIR microscopy enables <i>in situ</i> chemical measurement of heterogeneous materials and investigations on a range of chemical and physical transformations, including polymer surface reorganization, hydrogen-deuterium isotope exchange, and ethanol-induced denaturation of proteins. We also perform LiPFIR imaging of the budding site of yeast cell wall in the fluid as a demonstration of biological applications. LiPFIR unleashes the potential of in liquid AFM-IR for chemical nanoscopy.

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Subnanometer Spatial Resolution Chemical Imaging

10.2172/1461754 ◽

2018 ◽

Author(s):

Paul S. Weiss

Keyword(s):

Spatial Resolution ◽

Chemical Imaging

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Sub-10 nm spatial resolution for electrical properties measurements using bimodal excitation in electric force microscopy

Review of Scientific Instruments ◽

10.1063/5.0038335 ◽

2021 ◽

Vol 92 (2) ◽

pp. 023703

Author(s):

Khaled Kaja ◽

Denis Mariolle ◽

Nicolas Chevalier ◽

Adnan Naja ◽

Mustapha Jouiad

Keyword(s):

Electrical Properties ◽

Spatial Resolution ◽

Electric Force ◽

Force Microscopy ◽

Electric Force Microscopy

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Advanced Scheme to Generate MHz, Fully Coherent FEL Pulses at nm Wavelength

Applied Sciences ◽

10.3390/app11136058 ◽

2021 ◽

Vol 11 (13) ◽

pp. 6058

Author(s):

Georgia Paraskaki ◽

Sven Ackermann ◽

Bart Faatz ◽

Gianluca Geloni ◽

Tino Lang ◽

...

Keyword(s):

Repetition Rate ◽

High Harmonic ◽

High Repetition Rate ◽

Optical Cavities ◽

Electron Bunches ◽

High Repetition ◽

Average Brightness ◽

Technical Requirements ◽

Harmonic Content ◽

Unique Approach

Current FEL development efforts aim at improving the control of coherence at high repetition rate while keeping the wavelength tunability. Seeding schemes, like HGHG and EEHG, allow for the generation of fully coherent FEL pulses, but the powerful external seed laser required limits the repetition rate that can be achieved. In turn, this impacts the average brightness and the amount of statistics that experiments can do. In order to solve this issue, here we take a unique approach and discuss the use of one or more optical cavities to seed the electron bunches accelerated in a superconducting linac to modulate their energy. Like standard seeding schemes, the cavity is followed by a dispersive section, which manipulates the longitudinal phase space of the electron bunches, inducing longitudinal density modulations with high harmonic content that undergo the FEL process in an amplifier placed downstream. We will discuss technical requirements for implementing these setups and their operation range based on numerical simulations.

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Natural Science and Supernatural Thought Experiments

Religions ◽

10.3390/rel10060389 ◽

2019 ◽

Vol 10 (6) ◽

pp. 389

Author(s):

James Robert Brown

Keyword(s):

Natural Science ◽

Thought Experiment ◽

Thought Experiments ◽

The Other ◽

Space And Time ◽

Wide Range ◽

The Difference ◽

Theological Thought

Religious notions have long played a role in epistemology. Theological thought experiments, in particular, have been effective in a wide range of situations in the sciences. Some of these are merely picturesque, others have been heuristically important, and still others, as I will argue, have played a role that could be called essential. I will illustrate the difference between heuristic and essential with two examples. One of these stems from the Newton–Leibniz debate over the nature of space and time; the other is a thought experiment of my own constructed with the aim of making a case for a more liberal view of evidence in mathematics.

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