Characterizing and ultimately controlling the heterogeneity underlying biomolecular functions, quantum behavior of complex matter, photonic materials, or catalysis requires large-scale spectroscopic imaging with simultaneous specificity to structure, phase, and chemical composition at nanometer spatial resolution. However, as with any ultrahigh spatial resolution microscopy technique, the associated demand for an increase in both spatial and spectral bandwidth often leads to a decrease in desired sensitivity. We overcome this limitation in infrared vibrational scattering-scanning probe near-field optical microscopy using synchrotron midinfrared radiation. Tip-enhanced localized light-matter interaction is induced by low-noise, broadband, and spatially coherent synchrotron light of high spectral irradiance, and the near-field signal is sensitively detected using heterodyne interferometric amplification. We achieve sub-40-nm spatially resolved, molecular, and phonon vibrational spectroscopic imaging, with rapid spectral acquisition, spanning the full midinfrared (700-5,000 cm(-1)) with few cm(-1) spectral resolution. We demonstrate the performance of synchrotron infrared nanospectroscopy on semiconductor, biomineral, and protein nanostructures, providing vibrational chemical imaging with subzeptomole sensitivity.

https://www.pnas.org/content/pnas/111/20/7191.full.pdf

Ultrabroadband infrared nanospectroscopic imaging.

Coherent dual comb spectroscopy can provide high-resolution, high-accuracy measurements of a sample response in both magnitude and phase. We discuss the achievable signal-to-noise ratio (SNR) due to both additive white noise and multiplicative noise, and the corresponding sensitivity limit for trace gas detection. We show that sequential acquisition of the overall spectrum through a tunable filter, or parallel acquisition of the overall spectrum through a detector array, can significantly improve the SNR under some circumstances. We identify a useful figure of merit as the quality factor, equal to the product of the SNR, normalized by the square root of the acquisition time, and the number of resolved frequency elements. For a single detector and fiber-laser based system, this quality factor is 106 – 107 Hz1/2.

/pdf/sensitivity-of-coherent-dual-comb-spectroscopy-48y6fvs80i.pdf

Sensitivity of coherent dual-comb spectroscopy.

http://ir.yic.ac.cn/bitstream/133337/6993/2/Colorimetric%20sensing%20of%20copper%28II%29%20based%20on%20catalytic%20etching%20of%20gold%20nanorods.pdf

Colorimetric sensing of copper(II) based on catalytic etching of gold nanoparticles.

Among the different spectrometric techniques for trace analysis Laser Ionization Mass Spectrometry (LIMS) is well established as a trace analytical method. With the LIMS technique the sample material is evaporated and ionized by means of a focused pulsed laser in a laser microplasma, which is formed in the spot area of the irradiated sample. All chemical elements in the sample materials are evaporated and ionized in the laser plasma. The ions formed are separated according to their mass and energy by a time-of-flight, quadrupole or double focusing mass spectrometer. In this review the characteristics and analytical features, some recent developments and applications of laser ionization mass spectrometry in inorganic trace analysis are described.

Laser ionization mass spectrometry in inorganic trace analysis

https://escholarship.org/content/qt8j33g665/qt8j33g665.pdf?t=qnhkef

Synchrotron infrared nano-spectroscopy and -imaging

Es wird eine selektive Reaktion auf Lithium beschrieben, die auf der Schwerloslichkeit einer Verbindung des Lithiums mit Eisen(III)-perjodatsaure beruht. Die Reaktion ermoglicht einen sicheren Nachweis von einigen Zehnteln Gamma Lithium in einem Tropfen einer an anderen Alkalisalzen gesattigten Losung.

O. Pročke

Papers

Ein neuer empfindlicher Lithiumnachweis