Infrared spectroscopy

  • Article
    | Open Access

    Vibrational energy transfer (VET) is essential for protein function as it is responsible for efficient energy dissipation in reaction sites and is linked to pathways of allosteric communication. Here authors equipped a tryptophan zipper with a VET injector and a VET sensor for femtosecond pump probe experiments to map the VET.

    • Erhan Deniz
    • , Luis Valiño-Borau
    •  & Jens Bredenbeck
  • Article
    | Open Access

    Photosystem II subunit S (PsbS) senses thylakoid lumen acidification when plants are exposed to excess light. Here the authors use NMR and IR spectroscopy to show that low pH causes repositioning of an amphipathic helix and folding of a loop involving critical pH sensing glutamate residues in PsbS.

    • Maithili Krishnan-Schmieden
    • , Patrick E. Konold
    •  & Anjali Pandit
  • Article
    | Open Access

    Health status transitions are reflected as characteristic changes in molecular composition of biofluids. Here, the authors apply infrared molecular fingerprinting and reveal that blood-based phenotypes are sufficiently stable over time, providing the basis for time- and cost-effective health monitoring.

    • Marinus Huber
    • , Kosmas V. Kepesidis
    •  & Mihaela Žigman
  • Article
    | Open Access

    Glycolipids are glycoconjugates with important biological functions, but techniques for their analysis are deficient. Here, the authors report the use of cryogenic gas-phase infrared spectroscopy to investigate isomerism in a set of immunologically relevant glycolipids, and show that their structural features can be accurately resolved based on a narrow spectral fingerprint region.

    • Carla Kirschbaum
    • , Kim Greis
    •  & Kevin Pagel
  • Article
    | Open Access

    Quantized circular photogalvanic effect (CPGE) is predicted in chiral topological semimetals, but the experimental observation remains challenging. Here, Ni et al. observe a large topological longitudinal photocurrent in CoSi, which is much larger than the photocurrent in any other chiral crystals, indicating quantized CPGE within reach upon doping and increase of the hot-carrier lifetime.

    • Zhuoliang Ni
    • , K. Wang
    •  & Liang Wu
  • Article
    | Open Access

    Existing high-dimensional optical imaging techniques that record space and polarization cannot detect the photon’s time of arrival due to the limited speeds of electronic sensors. Here, the authors develop a single-shot ultrafast imaging modality to record light-speed high-dimensional events with picosecond resolution.

    • Mohammad A. Almajhadi
    • , Syed Mohammad Ashab Uddin
    •  & H. Kumar Wickramasinghe
  • Article
    | Open Access

    Eumelanin protects cells from sun damage and is promising for energy conversion applications, but its structure and excited state dynamics are elusive. Here the authors shed light on both aspects combining selective excitation of UV- and visible-absorbing chromophores with time-resolved infrared spectroscopy.

    • Christopher Grieco
    • , Forrest R. Kohl
    •  & Bern Kohler
  • Article
    | Open Access

    Nano-FTIR spectroscopy allows chemical characterization of composite surfaces, but its capability in subsurface analysis is not much explored. The authors show that spectra from thin surface layers differ from those of subsurface layers of the same organic material, and establish a method for distinguishing them in experiments.

    • Lars Mester
    • , Alexander A. Govyadinov
    •  & Rainer Hillenbrand
  • Article
    | Open Access

    Atomic force microscopy-infrared (AFM-IR) spectroscopic imaging techniques offer a non-perturbative, molecular contrast for characterization of nanomaterials; however, data are often complicated by the measurement apparatus, sample preparation conditions and low signal-to-noise ratio. Here, the authors demonstrate a closed-loop controlled AFM-IR instrument design to address measurement artifacts and reduce noise up to 5x compared to previous methods.

    • Seth Kenkel
    • , Shachi Mittal
    •  & Rohit Bhargava
  • Article
    | Open Access

    While infrared nanospectroscopy methods based on thermomechanical detection (AFM-IR) enables the acquisition of absorption spectra at the nanoscale, single molecule detection has not been possible so far. Here, the authors present off-resonance, low power and short pulse infrared nanospectroscopy (ORS-nanoIR), which allows measuring infrared absorption spectra at the single molecule level in a time scale of seconds with high throughput and demonstrate that the secondary structure of single protein molecules can be determined with this method.

    • Francesco Simone Ruggeri
    • , Benedetta Mannini
    •  & Tuomas P. J. Knowles
  • Article
    | Open Access

    Compact spectrometers can be useful in many applications and many sophisticated architectures have been proposed. In this work, the authors show that with an evaporating droplet on a fiber tip, spectrometry can be robustly and accurately performed with a simple and passive microfluidic system.

    • P. Malara
    • , A. Giorgini
    •  & G. Gagliardi
  • Article
    | Open Access

    Precision-spectroscopy techniques can accurately measure lines in constrained frequency and intensity ranges. The authors propose a spectroscopic-network-assisted precision spectroscopy method by which transitions measured in a narrow range provide information in other, extended regions of the spectrum.

    • Roland Tóbiás
    • , Tibor Furtenbacher
    •  & Wim Ubachs
  • Article
    | Open Access

    Polycyclic aromatic hydrocarbons (PAHs) are present in the interstellar medium but their origin is unclear. Here the authors investigate large PAH formation from smaller PAHs in a plasma jet by mass-selective IR and UV laser spectroscopy, uncovering diacetylene radical addition as formation mechanism.

    • Alexander K. Lemmens
    • , Daniël B. Rap
    •  & Anouk M. Rijs
  • Article
    | Open Access

    While main group elements possess four valence orbitals that are accessible for bonding, quadruple bonding to main group elements is very rarely observed. Here the authors report that boron is able to form four bonding interactions with iron in the BFe(CO)3- anion complex.

    • Chaoxian Chi
    • , Jia-Qi Wang
    •  & Jun Li
  • Article
    | Open Access

    Generally infrared and Raman spectroscopic methods are needed to study the symmetric and asymmetric molecular vibrational modes. Here the authors demonstrate complementary vibrational spectroscopy to organic molecules by simultaneously measuring their symmetric and anti-symmetric vibrations with one setup.

    • Kazuki Hashimoto
    • , Venkata Ramaiah Badarla
    •  & Takuro Ideguchi
  • Article
    | Open Access

    It has been challenging to probe whether dynamically disordered organic cations affect optical properties of CH3NH3PbI3. Here, Guo et al. employ infrared-pump electronic-probe spectroscopy and show that pump-induced atomic motions of the organic cations do not substantially alter optoelectronic properties.

    • Peijun Guo
    • , Arun Mannodi-Kanakkithodi
    •  & Richard D. Schaller
  • Article
    | Open Access

    Glycosyl cations are key intermediates in glycosylation reactions, but their structure has remained elusive due to their transient nature. Here, the authors perform an in-depth structural analysis and report that C2-participating protective groups induce acetoxonium cations with distinct ring conformations.

    • Eike Mucha
    • , Mateusz Marianski
    •  & Kevin Pagel
  • Article
    | Open Access

    Alumina is thought to be the main condensate to form in the gas outflow from oxygen-rich evolved stars. Here, the authors perform a condensation experiment with alumina in a low-gravity environment, and find spectroscopic evidence for a sharp feature at a wavelength of 13.55 μm.

    • Shinnosuke Ishizuka
    • , Yuki Kimura
    •  & Yuko Inatomi
  • Article
    | Open Access

    Large peatlands exist at high latitudes because flooded conditions and cold temperatures slow decomposition, so the presence of (sub)tropical peat is enigmatic. Here the authors show that low-latitude peat is preserved due to lower carbohydrate and greater aromatic content resulting in chemical recalcitrance.

    • Suzanne B. Hodgkins
    • , Curtis J. Richardson
    •  & Jeffrey P. Chanton
  • Article
    | Open Access

    Dual-comb spectroscopy is a powerful tool for realizing rapid spectroscopic measurements with high sensitivity and selectivity. Here, Yu et al. demonstrate silicon microresonator-based dual comb spectroscopy in the mid-infrared region, where strong vibrational resonances of many liquids exist.

    • Mengjie Yu
    • , Yoshitomo Okawachi
    •  & Alexander L. Gaeta
  • Article
    | Open Access

    X-ray spectroscopy is a tool used for the investigation of aqueous solutions but the strong absorption of water means that very thin liquid sheets are needed for accurate analysis. Here the authors produce free-flowing liquid sheets 2 orders of magnitude thinner than sheets obtained with existing techniques.

    • Jake D. Koralek
    • , Jongjin B. Kim
    •  & Daniel P. DePonte
  • Article
    | Open Access

    While transition metal complexes bearing terminal oxido ligands are common, those of group 11 elements have yet to be experimentally observed. Here, Riedel and colleagues synthesise molecular oxygen fluorides of copper, silver and gold, and show that the oxo ligands possess radical character.

    • Lin Li
    • , Tony Stüker
    •  & Sebastian Riedel
  • Article
    | Open Access

    Liquid water molecules are in constant vibrational motion, but probing how their local behaviour influences collective dynamics remains a challenge. Here, the authors present terahertz-infrared spectroscopy to elucidate coupling of the O-H stretch vibration to collective, delocalized intermolecular modes.

    • Maksim Grechko
    • , Taisuke Hasegawa
    •  & Mischa Bonn
  • Article
    | Open Access

    A deeper understanding of the mechanics of molecular machines is limited by the fast motions which are in the nanosecond or picosecond timescale. Here the authors present a real-time observation of structural changes in a rotaxane-based molecular shuttle by transient two-dimensional infrared spectroscopy.

    • Matthijs R. Panman
    • , Chris N. van Dijk
    •  & Sander Woutersen
  • Article
    | Open Access

    The electrodynamics of topological insulators has been predicted to show a new magnetoelectric term, but this hasn’t been observed. Here, Dziomet al. observe a universal Faraday rotation angle equal to the fine structure constant, evidencing the so-called topological magnetoelectric effect.

    • V. Dziom
    • , A. Shuvaev
    •  & L. W. Molenkamp
  • Article
    | Open Access

    The lithium solvation structure in the electrolyte solution for lithium-ion batteries has not been fully understood. Here, the authors show ultrafast fluxional exchange of carbonate solvent molecules in and out of lithium-ion solvation sheath utilizing coherent two-dimensional infrared spectroscopy.

    • Kyung-Koo Lee
    • , Kwanghee Park
    •  & Minhaeng Cho
  • Article
    | Open Access

    An ideal optical frequency-comb system should combine both single-line spectral resolution and a bandwidth broad enough to cover as many lines as possible. Here, the authors incorporate a fibre spectrometer to detect approximately 500 comb-lines with an instrument resolution of 120 megahertz.

    • Nicola Coluccelli
    • , Marco Cassinerio
    •  & Gianluca Galzerano
  • Article
    | Open Access

    Molecules on a metal surface may be modified by the presence of oxide layers, but further mechanistic understanding is still required. Here the authors show for methanol on rutile TiO2(110) that strongly bonded adsorbates lift surface relaxations, leading to substrate-mediated interaction between adsorbates.

    • David Silber
    • , Piotr M. Kowalski
    •  & Christof Wöll
  • Article
    | Open Access

    Use of electron microscopy to determine morphology, or find where functionally significant biomolecules are located with high spatial resolution is of great interest. Here, Rez, Cohen et al. use aloof electron beam vibrational spectroscopy to probe different bonds in biological samples with no significant radiation damage.

    • Peter Rez
    • , Toshihiro Aoki
    •  & Hagai Cohen
  • Article
    | Open Access

    Excitons—bound electron-hole pairs—in two-dimensional transition-metal dichalcogenides can exhibit a rich spectrum of excited states. Here, the authors use ultrafast mid-infrared spectroscopy to explore the dynamics of these so-called 1s-intraexcitonic transitions in monolayer molybdenum disulphide.

    • Soonyoung Cha
    • , Ji Ho Sung
    •  & Hyunyong Choi
  • Article
    | Open Access

    Understanding of electrolyte-electrode interfaces is limited due to the lack of suitable probing techniques. Here, the authors present a vibrational spectroscopy based on graphene gratings, which enables sensitive and interface-specific detection of molecular vibrations at electrolyte-electrode interfaces.

    • Ya-Qing Bie
    • , Jason Horng
    •  & Feng Wang
  • Article |

    Infrared spectral mapping offers the non-destructive analyses of samples; however, the spatial resolution is restricted to >10 microns. Here, the authors present a new infrared technique capable of sub-micron scale mineral identification, demonstrated using a chondrule and a cometary dust grain.

    • Gerardo Dominguez
    • , A. S. Mcleod
    •  & D. N. Basov
  • Article
    | Open Access

    Mid-infrared spectroscopy offers important chemical and structural information about biological samples but diffraction prevents nanoscale studies. Amenabar et al.demonstrate Fourier transform infrared nanospectroscopy for analysing the secondary structure of protein complexes with 30 nm spatial resolution.

    • Iban Amenabar
    • , Simon Poly
    •  & Rainer Hillenbrand