arXiv subjects

Daniela Täuber

Publications and source records attributed to Daniela Täuber.

6 recordsLinked to original sources

arXiv2026

Mid-infrared photo-induced force microscopy (IR-PiFM/PiF-IR) -- Answers to some questions

Mid-infrared photo-induced force microscopy (IR-PiFM/PiF-IR) enables high-resolution chemical imaging of surfaces with lateral resolution less than 5 nm. Here are some answers to questions about the physical background, practical handling and potential applications of PiF-IR including its use in the context of studying antimicrobial interaction. Such questions had been addressed to me during the Faraday Discussions on Vibrations at Interfaces which took place in April 2026 in Manchester/UK. The discussion was part of the theme "What is the question, what is the technique?" in the context of which I presented our recent work [James et al., Faraday Discussions, 2026, doi: 10.1039/d6fd00003g]. A modified version of this manuscript will be published in the themed collection "Vibrations at Interfaces" in Faraday Discussions.

cond-mat.mtrl-sci↗

arXiv2025

Effect of hybrid field coupling in nanostructured surfaces on anisotropic signal detection in nanoscale infrared spectroscopic imaging methods

Anisotropic intensity distributions on nanostructured surfaces and polarization-sensitive spectra have been observed in a number of nanoscale infrared spectroscopic imaging methods, including nano-FTIR [Bakir et al., Molecules, 2020, 25, 4295], photothermal induced resonance (PTIR) [Waeytens et al., Analyst, 2021, 146], tapping AFM-IR [Hondl et al., ACS Meas. Sci. Au, 2025, 5, 469; Luo et al., APL, 2022, 121, 23330], infrared photoinduced force microscopy (PiF-IR) [Anindo et al., JPCC, 2025, 129, 4517; Shcherbakov et al., Rev Methods Primers, 2025, 5, 1; Ali et al., Anal. Chem., 2025, 97, 23914] and peak force infrared microscopy (PFIR) [Xie et al., JPCC, 2022, 126, 8393; Anindo, JPCC, 2025]. A recent work combining modeling and experiment demonstrated that the hybrid field coupling of the IR illumination E0 with a polymer nanosphere and a metallic AFM probe is nearly as strong as the plasmonic coupling in case of a gold nanosphere [Anindo, JPCC, 2025]. For p-polarized illumination, this results in enhanced IR absorption on the surface perpendicular to the propagation of E0 which can explain the observed anisotropic intensity distribution. An additional anisotropy may be introduced by aligned surface molecules with oriented vibrational transition moments [Bakir et al., Molecules, 2020, 25, 4295; Luo, APL, 2022]. PiF-IR is strongly surface sensitive combining an unprecedented spatial resolution < 5 nm with high spectral resolution [Shcherbakov, Rev Methods Primers, 2025; Ali, Anal. Chem., 2025], which allows, for example, to visualize nanoscale chemical variation on the surface of bacteria cells affected by antimicrobial interaction [Ali, Anal. Chem., 2025]. We compare PiF-IR hyperspectra of aligned perylene Langmuir Blodgett monolayers on nanostructured and planar gold substrates and use quantum chemical calculations of the oriented vibrational oscillators to interpret the observations.

cond-mat.mes-hall↗

arXiv2025

Nano-chemical cell-surface evaluation in photothermal spectroscopic imaging of antimicrobial interaction in model system Bacillus subtilis & vancomycin

The power of photothermal spectroscopic imaging to visualize antimicrobial interaction on the surface of individual bacteria cells has been demonstrated on the model system Bacillus subtilis and vancomycin using mid-infrared photo-induced force microscopy (PiF-IR, also mid-IR PiFM). High-resolution PiF contrasts obtained by merging subsequent PiF-IR scans at two different illumination frequencies revealed chemical details of cell wall destruction after 30 and 60 min incubation with vancomycin with a spatial resolution of $\approx 5$ nm. This approach compensates local intensity variations induced by near-field coupling of the illuminating electric field with nanostructured surfaces, which appear in single-frequency contrasts in photothermal imaging methods, as shown by [Anindo et al., J. Phys. Chem C, 2025, 129, 4517]. Known spectral shifts associated with hydrogen bond formation between vancomycin and the N-acyl-D-Ala4-D-Ala5 termini in the peptidoglycan cell wall have been observed in chemometrics of PiF-IR spectra from treated and untreated Bacillus subtilis harvested after 30 min from the same experiment. Spectral signatures of the vancomyin interaction have been located in the piecrust of a progressing septum with $\approx 10$ nm resolution using PiF contrasts of three selected bands of a PiF-IR hyperspectral scan of an individual Bacillus subtilis cell harvested after 30 min incubation. Our results are complemented by a discussion of imaging artifacts and the influence of parameter settings supporting further development towards standardization in the application of PiF-IR for visualizing the chemical interaction of antibiotics on the surface of microbes with few nanometer resolution.

physics.bio-ph↗

arXiv2024

Photothermal Expansion of Nanostructures in Photo-induced Force Microscopy

Powerful mid-infrared illumination combined with mechanical detection via force microscopy provides access to nanoscale spectroscopic imaging in Materials and Life Sciences. Photo-induced force microscopy (PiFM) employs pulsed illumination and noncontact force microscopy resulting in unprecedented spatial and high spectral resolution. The near-field-enhanced light absorption in the materials leads to thermal expansion affecting the distance-dependent weak van der Waals (VdW) force acting between the tip and the sample. We model the non-linear impact of material characteristics and surface shape on the tip-sample interaction, the heat generation from the presence of a photo-induced electric field, the associated thermal expansion under different illumination conditions including light polarization and the feedback to the dynamic tip motion due to the expansion. Comparison of the results with our experimental investigation of a polymer nanosphere shows good agreement, contributing new insights into the understanding required for a quantitative analysis of nanostructured materials imaged using PiFM.

physics.optics↗

arXiv2016

Fluorescence correlation spectroscopy in thin films at reflecting substrates as a means to study nanoscale structure and dynamics at soft-matter interfaces

Structure and dynamics at soft-matter interfaces play an important role in nature and technical applications. Optical single-molecule investigations are non-invasive and capable to reveal heterogeneities at the nanoscale. In this work we develop an autocorrelation function (ACF) approach to retrieve tracer diffusion parameters obtained from fluorescence correlation spectroscopy (FCS) experiments in thin liquid films at reflecting substrates. This approach then is used to investigate structure and dynamics in 100 nm thick 8CB liquid crystal films on silicon wafers with five different oxide thicknesses. We find a different extension of the structural reorientation of 8CB at the solid-liquid interface for thin and for thick oxide. For the thin oxides, the perylenediimide tracer diffusion dynamics in general agrees with the hydrodynamic modeling using no-slip boundary conditions with only a small deviation close to the substrate, while a considerably stronger decrease of the interfacial tracer diffusion is found for the thick oxides.

cond-mat.soft↗

arXiv2015

Influence of van der Waals interactions on morphology and dynamics in ultrathin liquid films at silicon oxide interfaces

Single molecule tracer diffusion studies of evaporating (thinning) ultrathin tetrakis-2-ethyl-hexoxysilane (TEHOS) films on silicon with 100 nm thermal oxide reveal a considerable slowdown of the molecular mobility within less than 4 nm above the substrate (corresponding to a few molecular TEHOS layers). This is related to restricted mobility and structure formation of the liquid in this region, in agreement with information obtained from a long-time ellipsometric study of thinning TEHOS films on silicon substrates with 100 nm thermal or 2 nm native oxide. Both show evidence for the formation of up to four layers. Additionally, on thermal oxide, a lateral flow of the liquid is observed, while the film on the native oxide forms an almost flat surface and shows negligible flow. Thus, on the 2 nm native oxide the liquid mobility is even more restricted in close vicinity to the substrate as compared to the 100 nm thermal oxide. In addition, we found a significantly smaller initial film thickness in case of the native oxide under similar dipcoating conditions. We ascribe these differences to van der Waals interactions with the underlying silicon in case of the native oxide, whereas the thermal oxide suffices to shield those interactions.

cond-mat.soft↗