BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Memento EPFL// BEGIN:VEVENT SUMMARY:IMX Talks - Infrared correlation nanoscopy with unprecedented s pectral coverage DTSTART:20250516T110000 DTEND:20250516T120000 DTSTAMP:20260921T222114Z UID:f91d1bd230f2b6d6299887f3cc426e10d8ff6383e3b9410bd18ebecc CATEGORIES:Conferences - Seminars DESCRIPTION:Dr. Bogdan Sava\, Attocube Systems AG\, Germany\nNANOSCALE res olved imaging and spectroscopy using scattering-type Scanning Near-field O ptical Microscopy (s-SNOM) or tapping AFM-IR (local detection of photother mal expansion) enables bypassing the diffraction limit of light and to ach ieve a wavelength-independent spatial resolution of < 20 nm in the infrare d (IR) frequency range [1\,2]. Measurements have successfully demonstrated a wide range of analytical capabilities for e.g. nanoscale chemical mappi ng and material identification [3]\, conductivity profiling [4\,5]\, deter mination of secondary structure of individual proteins [6] and vector fiel d mapping [7]\, making them a trusted tool for surface analysis in many br anches of sciences and technology.\nWhile s-SNOM and tapping AFM-IR provid e nanoscale spatial resolution\, applications are often limited by limited availability of illumination source\, which prevents studies of low energ y phonons\, polaritons\, and molecular vibrations. This problem is partial ly circumvented by nanoscale Fourier transform infrared spectroscopy (nano -FTIR) – a potent s-SNOM technique – which can achieve large spectral coverage down to 320 cm-1 (ca. 31 µm wavelength) using ultrabroadband inf rared radiation from synchrotrons [8]. However\, singe-frequency\, nanosca le resolved imaging in the far-IR spectral range at wavelengths of e.g.\, > 12 µm that provide rapid mapping of fields or materials properties rema ins challenging due to lack of suitable table-top light sources with suffi ciently small bandwidth (e.g.\, < 10 cm-1).\nIn this work we demonstrate s -SNOM and tapping AFM-IR imaging and spectroscopy based on a fully integra ted and automated commercial OPO laser source covering the spectral range from 1.5 – 18.2 µm (ca. 7100 – 540 cm-1) with narrow linewidth < 4 cm -1 in the entire tuning range. To illustrate the capabilities of this ligh t source\, Fig. 1 shows selective mapping of the nanoscale spatial distrib ution of PVAC in a PS polymer matrix based on the 698 cm-1 and 1725 cm-1 a bsorption lines\, allowing to study characteristic material heterogeneity and interfaces in the far-IR spectral range. Obtained results have been ve rified by correlative AFM-IR imaging with operating the laser at selected repetition rates. It is worth mentioning that sweeping the laser frequency also allows to measure spectroscopic signatures of materials and other na nostructures with unprecedented spectral coverage\, enabling studies of fu ndamental molecular resonances and quantum states in the long wavelength I R spectral range\, which until now was not possible.\nFurther\, Fig. 2 sho ws a ca. 34 nm thin hBN flake on a SiO2 substrate imaged by s-SNOM with in terferometric detection to obtain nanoscale resolved amplitude and phase i mages of the propagating surface phonon-polariton (SPhP) mode. Clearly\, t he amplitude image at 810 cm-1 reveals the characteristic fringe pattern a t the edge of the flake\, stemming from propagating SPhP in the lower Rest strahlenband\, launched by the AFM probing tip. Accessing the lower Restst rahlenband in hBN for nanoscale resolved far-IR imaging and spectroscopy i s unique and unprecedented and is a first demonstration of the capabilitie s of the presented light source for s-SNOM experiments to study polaritons in different material systems and devices.\n\n[1] F. Keilmann\, R. Hillen brand. Philosophical Transactions of the Royal Society A: Mathematical\, P hysical and Engineering Sciences\, 362\, 787–805\, (2004).\n[2] J. Jahng \, et al.\,. PNAS\, 116\, 26359-26366\, (2019).\n[3] F. Huth at al.\, Nano Letters\, 12\, 8\, 3973-3978 (2012).\n[4] J. Stiegler et al.\, Nano Lette rs\, 10\, 4\, 1387-1392 (2010).\n[5] N. A. Aghamiri et al.\, Optics Expres s\, 27\, 17\, 24231-24242\, (2019).\n[6] I. Amenabar et al.\, Nature Commu nications\, 4\, 2890 (2013).\n[7] P. Alonso-González\, Nature Communicati ons\, 3\, 684 (2012).\n[8] O. Khatib\, et al.\, ACS Phot.\, 5\, 2773-2779 (2016).\n[9] Q. Zhang\, et al.\, Nature\, 597\, 187-195 (2021).\n\nBio: Bo gdan Sava works as an application scientist at attocube systems AG\, busin ess department "nanoscale analytics". With a background in physics and div erse expertise in near-field using sSNOM (scattering type scanning near fi eld optical microscopy) technology\, accumulated over the last 6 years at attocube\, Bogdan has proven track record in conducting research with expe rts from different fields of science (photonics\, chemistry\, material sci ence\, surface investigation etc) in a very efficient way.\n  LOCATION:MXF 312 https://plan.epfl.ch/?room==MXF%20312 STATUS:CONFIRMED END:VEVENT END:VCALENDAR