Molecular alignment underpins optical, mechanical, and thermal properties of materials, however, its direct measurement from volumes with micrometer dimensions is not accessible, especially, for structurally complex bio-materials. How the molecular alignment is linked to extraordinary properties of silk and its amorphous-crystalline composition has to be accessed by a direct measurement from a single silk fiber. Here, we show orientation mapping of the internal silk fiber structure via polarisation-dependent IR absorbance at high spatial resolution of 4.2 μm and 1.9 μm in a hyper-spectral IR imaging by attenuated total reflection using synchrotron radiation in the spectral fingerprint region around 6 μm wavelength. Free-standing longitudinal micro-slices of silk fibers, thinner than the fiber cross section, were prepared by microtome for the four polarization method to directly measure the orientational sensitivity of absorbance in the molecular fingerprint spectral window of the amide bands of β-sheet polypeptides of silk. Microtomed lateral slices of silk fibers, which may avoid possible artefacts that affect spectroscopic measurements with fibers of an elliptical cross sections were used in the study. Amorphisation of silk by ultra-short laser single-pulse exposure is demonstrated.

Anisotropy of absorbance (dichroism) and birefringence limits spatial resolution, sensitivity during quantitative detection of trace analytes, as well as spectral imaging in the near-IR and mid-IR spectral ranges. Here we show hyperspectral imaging capable of determining retardance and absorbance due to small changes in the real and imaginary parts of the refractive index ∼Δn and ∼Δκ at each single point of a measurement at diffraction limited resolution. This single-beam technique allows the retrieval of the phase and amplitude information by virtue of a twice different angular dependence of Δn and Δκ on the sample orientation angle. It has potential applications in analytical science, multi-dimensional optical memory devices, and forensic/defense/sensor fields.

A thermocouple of Au-Ni with only 2.5-μm-wide electrodes on a 30-nm-thick Si₃N₄ membrane was fabricated by a simple low-resolution electron beam lithography and lift off procedure. The thermocouple is shown to be sensitive to heat generated by laser as well as an electron beam. Nano-thin membrane was used to reach a high spatial resolution of energy deposition and to realise a heat source of sub-1 μm diameter. This was achieved due to a limited generation of secondary electrons, which increase a lateral energy deposition. A low thermal capacitance of the fabricated devices is useful for the real time monitoring of small and fast temperature changes, e.g., due to convection, and can be detected through an optical and mechanical barrier of the nano-thin membrane. Temperature changes up to ~2 × 10⁵ K/s can be measured at 10 kHz rate. A simultaneous down-sizing of both, the heat detector and heat source strongly required for creation of thermal microscopy is demonstrated. Peculiarities of Seebeck constant (thermopower) dependence on electron injection into thermocouple are discussed. Modeling of thermal flows on a nano-membrane with presence of a micro-thermocouple was carried out to compare with experimentally measured temporal response.

Polarised light imaging microscopy, with the addition of a liquid crystal (LC) phase retarder, was used to determine the birefringence of silk fibres with high (∼1 μm) spatial resolution. The measurement was carried out with the silk fibres (the optical slow axis) and the slow axis of the LC-retarder set at parallel angles. The direct fit of the transmission data allowed for high fidelity determination of the birefringence Δn ≈ 1.63 × 10⁻² (with ∼2% uncertainty) of the brown silk fibre, (Antheraea pernyi) averaged over the wavelength range λ = (425–625) nm. By measuring retardance at four separate wavelengths, it was possible to determine the true value of the birefringence of a thicker sample when an optical path may include a large number of wavelengths. The numerical procedures and required hardware are described for the do-it-yourself assembly of the imaging polariscope at a fractional budget compared to commercial units.

Large surface area samples of nanotextured black CuO were prepared by chemical etching of Cu for use in surface-enhanced Raman scattering (SERS). The SERS intensity of a self-assembled monolayer (SAM) of thiophenol was proportional to the thickness of a nanoscale-conformal Au film deposited by magnetron sputtering over the black CuO. A very high SERS yield of ∼10⁴ counts per s per mW was observed for the thiophenol SAM on the thickest Au films studied here. Synchrotron X-ray photoelectron spectroscopy was used to confirm that the surface of the chemically etched Cu was covered by high purity CuO. IR spectral characterization of the black CuO showed a close to linear increase in reflectivity from 25 to 100% over the range of 4000–500 cm⁻¹ wavenumbers (or 2.5–20 μm in wavelength). Sensing applications and thermal effects in SERS are discussed.