Facility Description

SISSI-Bio offline Instruments

Fourier Transform infrared spectroscopy (FTIR spectroscopy) may be performed at SISSI-Bio Offline by exploiting a large variety of interferometric systems and associated accessories. The VERTEX 70v (see Figure 1) is an in-vacuum interferometer that may operate in the Mid (MIR) and Far (FIR) infrared regimes, by using single point DTGS/MCT and bolometric detection schemes, respectively. A special technology capable to cover the FIR and MIR in a single scan, named Bruker FM, is also available. Conventional transmission measurements may be done and accessories for Attenuated Total Reflection (ATR) and Infrared Reflection Absorption Spectroscopy accessory (IRRAS), as well as diamond compression cells are also available.

 

The off-line facility is also equipped with the ALPHA II (See Figure 2) compact interferometer by Bruker (PRP@CERIC*). Conceived for being portable and easy to use, the ALPHA II system is equipped for ATR and reflection non-contact measurements, particularly useful for surface analysis of bulky samples.
An additional VERTEX 70 interferometer is also available.

Figure 1 VERTEX 70v interferometer coupled with Hyperion 3000 microscope

Vertex 70v interferometer Technical Specifications Spectral Ranges & Sources MIR to FIR Internal MIR and External water cooled MIR Detectors Room-T DTGS detectors, up to 60 cm-1; Nitrogen Cooled MCT detector up to 650 cm-1 Beamsplitters KBr and FIR/MIR-silicon Accessories single reflection PIKE Miracle (Ge, Si, diamond IREs) grazing angle single reflection G-ATR Harrick Scientific (Ge IREs) 25-reflections Harrick scientific (Ge, Si, ZnSe IRE) monolithic diamond ATR PLATINUM (Bruker) diamond compression cell (2 mm culet) diamond anvil cell (800 µm culet) demountable FTIR transmission cell (Harrick Scientific) A513/Q Variable angle reflection IRRAS accessory by Bruker

 

Figure 2 ALPHA II at SISSI-Bio offline

ALPHA II Technical Specifications Spectral Range  500 - 6000 cm-1 Spectral Resolution  Better than 2 cm-1 Accessories ZnSe Single Reflection ATR module; Contactless Reflection module

SISSI-Bio offline features two FTIR microscopes, for correlating the morphological features of a sample with its local chemistry in the MIR. The Hyperion 3000 Vis/IR microscope (see Figure 1), coupled with the vertex 70v microscope, is equipped with a single point MCT detector for single point measurements and hyperspectral mapping. It also mounts a bidimensional Focal Plane Array (FPA) detector for hyperspectral imaging (64X64 pixels). Transmission, reflection, grazing incidence and micro-ATR sampling modalities are possible (15X, 36X objectives; micro-ATR objective; grazing incidence (GIR) objective). In addition, a FTIR-600 Linkam cell devoted to dedicated T-dependent studies (-195°C-600°C) may be exploited.
A new Bruker Hyperion II microscope coupled with the INVENIO-II interferometer (see Figure 3) has been recently installed (PRP@CERIC*). With respect to the Hyperion 3000 microscope, the Hyperion II mounts a larger FPA detector (128x128 pixels) for faster imaging of wider areas. The system is also devoted to IR tomography measurements (See Figure 3).

Figure 3 Hyperion II microscopes coupled with INVENIO-II interferometer

Technical Specifications	Hyperion 3000	Heperion II
Spectral Range	MidIR	MidIR
Single Point Detector	Liquid nitrogen coooled MCT-A detector	Liquid nitrogen coooled MCT-Bdetector
Imaging Detector	64x64 pixels Focal Plane Array	128x128 pixels Focal Plane Array
Accessories		TomoIR setup
	15X, 36X objectives micro-ATR objective grazing incidence (GIR) objective FTIR-600 Linkam cell in-house build fluidic cells and tomo-IR setup IR Tomographic setup

 

A microscopy endstation for vibrational hyperspectral mapping and imaging with sub-micrometer lateral resolution is available (see Figure 4). The former experimental station is based on the so-called optical photothermal infrared (O-PTIR) microscopy, also known as Midinfrared photothermal (MIP) microscopy (PRP@CERIC*). The O-PTIR approach may be summarized as an IR-pump/visible probe approach. It works by illuminating a sample with pulsed IR radiation, from a tunable IR quantum cascade laser (QCL). When IR light excites molecular bonds within a sample, a portion of the energy absorbed and dissipated in the sample results in localized heating that, in turn, causes a reduction of the index of refraction of the IR-heated regions. An optical probe beam, i.e. a green-laser, detects the IR-induced changes that alter the intensity and angular distribution of probe light reflected, scattered, and/or transmitted by the sample. O-PTIR microscopy is diffraction limited. However, despite conventional IR microscopes, the aforementioned limit is imposed but the probing visible laser. Considering that visible light wavelengths are on average 1 order of magnitude shorted than Mid-IR wavelengths, the achievable lateral resolution is about a factor 10 better, allowing to switch from the micron to the sub-micron scale.
In addition, O-PTIR supports simultaneous Raman microscopy: sample scattered light may be separated by a dichroic mirror: elastic scattered light is exploited for probing IR sample absorption, whereas inelastic scattered light is sent to a Raman spectrometer for the generation of Raman spectra. As such, the IR and Raman measurements are obtained at the same time, same location, and same spatial resolution. In addition, fluorescence microscopy is also combined within the same instrument.
For more details on the technique and application, the reader may refer to the following recent paper: Craig B. Prater, Mustafa Kansiz, Ji-Xin Cheng; A tutorial on optical photothermal infrared (O-PTIR) microscopy. APL Photonics 1 September 2024; 9 (9): 091101.

Figure 4 O-PTIR microscope for IR-Raman-FL microscopy and imaging

Technical Specifications O-PTIR IR Source Quantum Cascade Laser 300-2700 &1800-950 cm-1 Visible source  Green Laser 532 nm Detectors Silicon Photodiode & Ultra Low power Laser (Avalanche Photodiode) detectors Objectives Cassegrain Vis-IR objective (40X, 0.8 NA); Vis Objective: 10X, 40X coverslip coprrected , 50X Acquisition modalities Co/propagation and Counter/propagation modalities, both reflection and transmission geometries Mapping and Imaging capabilities Technical Specification colocalized Raman Excitation wavelength Green Laser 532 nm Raman spectral range 3600 to 200 cm-1 Grating 600gr/mm 500nm blazed grating Detector CCD camera with thermoelectrically cooled head  Technical Specification colocalized epifluorescence Filters Ex: 350 nm / Em: 470 nm Ex: 469 nm / Em: 525 nm Ex: 559 nm / Em: 630 nm Camera 4.2 MP high speed monochrome camera, Ultra sensitive, >90% quantum efficiency

  

At SISSI-Bio offline, users may also perform vibrational analysis at the nanoscale exploiting the possibility offered by the near-field NeaSNOM microscope, by Attocube GmbH (see Figure 5). The equipment is suitable for surface analysis by IR scattering-type scanning near field optical microscopy (IR s-SNOM) in the 670-1800 cm^-1 spectral with a DFG laser source (nano-FTIR module) and Photo Thermal Expansion imaging feature AFM-IR modality of the instrument (NIM module) with a QCL laser source.

Figure 5 NeaSNOM microscope. NIM and nano-FTIR module may be seen on the left and the right respectively.

neaSNOM microscope Technical Specifications nano-FTIR module Technical Specifications Source DFG Laser Source (1800 to 800 cm-1) Detector Liquid nitrogen cooled MCT detector Imaging Modalities FTIR nanoscopy, 8 cm-1 spectral resolution Hyperspectral mapping Imaging NIM module Techncial Specifications Source QCL 1800-850 cm-1 Detector 4 quadrant photodiode (same of AFM) Imaging Modalities PTE, AFM-IR and AFM-IR+ modalities for single point spectroscopy and 2D imaging

*under the  PNRR (National Recovery and Resilience Plan) project Pathogen Readiness Platform for CERIC-ERIC upgrade (PRP@CERIC), under Mission 4 “Education and Research”, Component 2 “From Research to Enterprise”, Investment Line 3.1 “Fund for the creation of an integrated system of research and innovation infrastructures”,” funded by the European Union – Next Generation EU".