Study Of Fundamental Physics Research Articles

Synthesis of submillimeter-size two-dimensional metal iodides single crystal via undercooling control strategy

Two-dimensional (2D) metal iodides have attracted significant attention in recent years due to their superior optoelectronic properties. However, the current synthesis methods for 2D metal iodides are either time-consuming or not able to synthesize large size crystal. Here we develop an undercooling control strategy based on hot plate assisted vertical vapor deposition for the synthesis of submillimeter-size 2D bismuth iodide (BiI3) single crystal. The whole synthesis process is efficient and only takes one minute in atmosphere. The problem of high nucleation density can be addressed by undercooling control, avoiding the collide of crystals before they grow into large size. This general approach is versatility and can be expanding to synthesize other 2D metal iodides. In addition, nonlinear optical property investigation of BiI3 crystal reveals a thickness-dependent and power-dependent second harmonic response. Our strategy presents a new solution for facile preparation of large-size 2D metal iodides, facilitating their fundamental physics studies and next-generation optoelectronics development.

Cooling positronium to ultralow velocities with a chirped laser pulse train

When laser radiation is skilfully applied, atoms and molecules can be cooled1–3, allowing the precise measurements and control of quantum systems. This is essential for the fundamental studies of physics as well as practical applications such as precision spectroscopy4–7, ultracold gases with quantum statistical properties8–10 and quantum computing. In laser cooling, atoms are slowed to otherwise unattainable velocities through repeated cycles of laser photon absorption and spontaneous emission in random directions. Simple systems can serve as rigorous testing grounds for fundamental physics—one such case is the purely leptonic positronium11,12, an exotic atom comprising an electron and its antiparticle, the positron. Laser cooling of positronium, however, has hitherto remained unrealized. Here we demonstrate the one-dimensional laser cooling of positronium. An innovative laser system emitting a train of broadband pulses with successively increasing central frequencies was used to overcome major challenges posed by the short positronium lifetime and the effects of Doppler broadening and recoil. One-dimensional chirp cooling was used to cool a portion of the dilute positronium gas to a velocity distribution of approximately 1 K in 100 ns. A major advancement in the field of low-temperature fundamental physics of antimatter, this study on a purely leptonic system complements work on antihydrogen13, a hadron-containing exotic atom. The successful application of laser cooling to positronium affords unique opportunities to rigorously test bound-state quantum electrodynamics and to potentially realize Bose–Einstein condensation14–18 in this matter–antimatter system.

Dead-zone suppression method of NMOR atomic magnetometers based on alignment and orientation polarization

Nonlinear magneto-optical rotation (NMOR) atomic magnetometers demonstrate exceptional sensitivity in the geomagnetic environment, making them highly attractive for applications in resource exploration, biological research, and fundamental physics studies. Nevertheless, the presence of the “dead zone” hampers the magnetometer’s capacity to detect magnetic fields with sensitivity. In this paper, we present a method for effectively mitigating the “dead zone” by simultaneous detection of alignment and orientation polarization. Based on the standard formalism of density matrix and Liouville Equation, theoretical models of alignment and orientation resonance signals as a function of the magnetic field are developed. Additionally, due to the large light intensity used in the actual system, the alignment to orientation conversion (AOC) effect has been taken into account to reveal a more complete model. The influence of light intensity on the alignment and orientation signals are investigated. It is found that there is an optimal theoretical light intensity, which makes the suppression effect of the “dead zone” best. The theoretical model aligns well with the experimental phenomenon and successfully minimizes the extent of the “dead zone”.

Room Temperature Emission Line Narrowing and Long‐Range Photon Transport in Colloidal Quantum Wells Coupled to Metasurface Resonance

AbstractHighly efficient and spectrally pure single photon sources are desirable in fundamental studies of quantum physics and in many varied applications like in quantum metrology and quantum cryptography. 2D semiconductor colloidal quantum wells (CQWs) are quite appropriate as nanoscale photon sources because of their giant oscillator strengths and large absorption cross sections. The integration of such sources with dielectric metasurfaces exhibiting narrow resonances provides an excellent platform for highly efficient light‐matter interactions and the development of on‐chip light sources with high spectral purity. Here details on the use of capillary filling method are reported to achieve photonic coupling of CQWs to a metasurface resonator (MSR) featuring a square‐lattice geometry of holes on a slab‐waveguide to achieve strongly enhanced and almost spectrally pure emission of ≈3% of the original out‐of‐plane emission line‐width of the quantum emitters at room temperature. Long‐range exciton‐mediated photon transport facilitated by in‐plane slab waveguide modes is demonstrated and a theoretical basis to explain all the experimental data including that in terms of the MSR‐modified Lamb shifts and Purcell decays is provided. The results demonstrate a new platform with emergent photonic properties and suggest possibility of their use in on‐chip photonic quantum information processing.

Design of a novel ECR ion trap facility for nuclear physics and fundamental plasma processes studies

An innovative ECR ion trap facility, called PANDORA (Plasma for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry), was designed for fundamental plasma processes and nuclear physics investigations. The overall structure consists of three subsystems: a) a large (70 cm in length, 28 cm in inner diameter) ECR plasma trap with a fully superconducting B-minimum magnetic system (Bmax = 3.0 T) and an innovative design to host detectors and diagnostic tools; b) an advanced non-invasive plasma multidiagnostics system to locally characterize the plasma thermodynamic properties; c) an array of 14 HPGe detectors. The PANDORA facility is conceived to measure, for the first time, in-plasma β-decaying isotope rates under stellar-like conditions. The experimental approach consists in a direct correlation of plasma parameters and nuclear activity by disentangling - by means of the multidiagnostic system that will work in synergy with the γ-ray array - the photons emitted by the plasma (from microwave to hard X-ray) and γ-rays emitted after the isotope β-decay. In addition to nuclear physics research, fundamental plasma physics studies can be conducted in this unconventional ion source equipped with tens of detection and diagnostic devices (RF polarimeter, optical emission spectroscopy (OES), X-ray imaging, space and time-resolved spectroscopy, RF probes, scope), with relevant implications for R&D of ion sources for accelerator physics and technology. Several studies have already been performed in downsized nowadays operating ECRIS. Stable and turbulent plasma regimes have been described quantitatively, studying the change of plasma morphology, confinement, and dynamics of losses using space resolved X-ray spectroscopy.

Fundamental physics studies in time domain and multi-messenger astronomy

The era of ime domain and multi-messenger astronomy is not only leading to the development of a much broader set of detectors and instruments for astrophysical observations, but is also providing the means for astronomy to tie directly to cutting-edge studies in physics. In this manner, fundamental physics (theory and experiment) coupled with a strong theoretical understanding of astrophysical phenomena (guided by high-performance computing simulations) can tie directly to the amazing new observations in astronomy. This paper discusses how physics, astrophysical models, and observations can not only help astronomy probe fundamental physics but guide the needs for next-generation astrophysical missions.

Graph learning for particle accelerator operations.

Particle accelerators play a crucial role in scientific research, enabling the study of fundamental physics and materials science, as well as having important medical applications. This study proposes a novel graph learning approach to classify operational beamline configurations as good or bad. By considering the relationships among beamline elements, we transform data from components into a heterogeneous graph. We propose to learn from historical, unlabeled data via our self-supervised training strategy along with fine-tuning on a smaller, labeled dataset. Additionally, we extract a low-dimensional representation from each configuration that can be visualized in two dimensions. Leveraging our ability for classification, we map out regions of the low-dimensional latent space characterized by good and bad configurations, which in turn can provide valuable feedback to operators. This research demonstrates a paradigm shift in how complex, many-dimensional data from beamlines can be analyzed and leveraged for accelerator operations.

Position‐Selective Introduction of Ferromagnetism on the Micro‐ and Nanoscale in a Paramagnetic Thin Palladium Film

Postsynthetic, position‐selective addition of properties to materials constitutes a paradigm shifting step in materials engineering. The approach enables creation of material systems inaccessible by equilibrium and near‐equilibrium synthesis and can be applied in novel practical applications as well as fundamental physics studies over a range of length and energy scales. Ion implantation is a versatile, scalable, industry‐compatible tool, enabling the next step in this development. Herein, ion implantation is used to design and functionalize a mesoscopic magnetic architecture. A self‐supporting mask is combined with implantation of 60 keV Fe ions to create an embedded array of ≈8 μm‐wide circular ferromagnetic regions in a Pd film. The approach is contactless, free from surface residues, and requires no focusing or scanning of the beam. Magnetic properties of the array are probed with longitudinal magneto‐optic Kerr effect measurement while varying sample temperature and applied magnetic field. Microstructures are visualized with Kerr microscopy and compared to the Fe distribution measured with microbeam proton‐induced X‐Ray emission. Sample topography after implantation is obtained by atomic force microscopy, while ion beam analysis is used to probe concentration depth profiles of implanted Fe, impurities, and to investigate material mixing.

Creation of flexible spin-caloritronic material with giant transverse thermoelectric conversion by nanostructure engineering

Functional materials such as magnetic, thermoelectric, and battery materials have been revolutionized through nanostructure engineering. However, spin caloritronics, an advancing field based on spintronics and thermoelectrics with fundamental physics studies, has focused only on uniform materials without complex microstructures. Here, we show how nanostructure engineering enables transforming simple magnetic alloys into spin-caloritronic materials displaying significantly large transverse thermoelectric conversion properties. The anomalous Nernst effect, a promising transverse thermoelectric phenomenon for energy harvesting and heat sensing, has been challenging to utilize due to the scarcity of materials with large anomalous Nernst coefficients. We demonstrate a remarkable ~ 70% improvement in the anomalous Nernst coefficients (reaching ~ 3.7 µVK−1) and a significant ~ 200% enhancement in the power factor (reaching ~ 7.7 µWm−1K−2) in flexible Fe-based amorphous materials by nanostructure engineering without changing their composition. This surpasses all reported amorphous alloys and is comparable to single crystals showing large anomalous Nernst effect. The enhancement is attributed to Cu nano-clustering, facilitating efficient transverse thermoelectric conversion. This discovery advances the materials science of spin caloritronics, opening new avenues for designing high-performance transverse thermoelectric devices for practical applications.

Valleytronics Meets Straintronics: Valley Fine Structure Engineering of 2D Transition Metal Dichalcogenides

Abstract2D transition metal dichalcogenides (TMDs) have emerged as a novel class of semiconductors with promising applications in optoelectronics, owing to their rich and tunable valley fine structure, known as valleytronics. Strain engineering in TMDs presents opportunities to tailor their valley fine structures and band alignment, which greatly expands the potential to investigate their intrinsic properties and improve device performance, thus opening a new field of straintronics. In this review, recent advances in strain‐engineered 2D TMDs are summarized, with a focus on new phenomena and applications enabled by precision tuning of valley physics. The underlying mechanisms and connections are delineated between strain‐induced modifications to the valley fine structures based on intravalley, intervalley, and interlayer band alignment in single and heterostructure TMDs. These insights allow targeted strain control strategies to be devised for optimizing optoelectronic characteristics. This review provides perspectives and guidance on the future directions of valley‐straintronics and flexible 2D optoelectronics using TMDs, highlighting the substantial promise of valley‐strain engineering in TMDs for fundamental valley physics studies as well as practical device applications.

Air-Stable, Large-Area 2D Metals and Semiconductors.

Two-dimensional (2D) materials are popular for fundamental physics study and technological applications in next-generation electronics, spintronics, and optoelectronic devices due to a wide range of intriguing physical and chemical properties. Recently, the family of 2D metals and 2D semiconductors has been expanding rapidly because they offer properties once unknown to us. One of the challenges to fully access their properties is poor stability in ambient conditions. In the first half of this Review, we briefly summarize common methods of preparing 2D metals and highlight some recent approaches for making air-stable 2D metals. Additionally, we introduce the physicochemical properties of some air-stable 2D metals recently explored. The second half discusses the air stability and oxidation mechanisms of 2D transition metal dichalcogenides and some elemental 2D semiconductors. Their air stability can be enhanced by optimizing growth temperature, substrates, and precursors during 2D material growth to improve material quality, which will be discussed. Other methods, including doping, postgrowth annealing, and encapsulation of insulators that can suppress defects and isolate the encapsulated samples from the ambient environment, will be reviewed.

Cyclotron-based production of innovative medical radionuclides at the INFN-LNL: state of the art and perspective

The production of medical radionuclides is one of the research activities carried out in the framework of the SPES (Selective Production of Exotic Species) project under the completion stage at the Legnaro National Laboratories of the National Institute for Nuclear Physics (INFN-LNL). The heart of SPES is the 70-MeV proton cyclotron having a dual-beam extraction, installed and commissioned in a new building equipped with ancillary laboratories currently under construction. The SPES main goal is the realization of an advanced ISOL (Isotope Separation On-Line) facility to produce re-accelerated exotic ion beams for fundamental nuclear physics studies. The cyclotron double-beam extraction system allows to simultaneously carry out applied research, such as radionuclides production for medicine (SPES-γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma$$\\end{document}). This paper summarizes the results obtained with the interdisciplinary projects LARAMED (LAboratory of RAdionuclides for MEDicine) and ISOLPHARM (ISOL technique for radioPHARMaceuticals). The first one, based upon the direct activation method, is focused on the production of the radionuclides under the spotlight of the international community (e.g., 99m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{99m}$$\\end{document}Tc, 67\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{67}$$\\end{document}Cu, 52/51\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{52/51}$$\\end{document}Mn, 47\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{47}$$\\end{document}Sc and Tb isotopes), from the nuclear cross-section measurements up to the preclinical studies. The other one exploits the ISOL technique for the development and production of radioisotopes with high-specific activity, such as 111\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{111}$$\\end{document}Ag, going beyond the state of the art in the field. The most recent SPES-γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma$$\\end{document} research activities and future perspective are here described, characterized by a consolidated network of collaborations with national and international institutions.

Design of the Lanthanum hexaboride based plasma source for the large plasma device at UCLA

The Large Plasma Device (LAPD) at UCLA (University of California, Los Angeles) produces an 18 m long, magnetized, quiescent, and uniform plasma at a high repetition rate to enable studies of fundamental plasma physics. Here, we report on a major upgrade to the LAPD plasma source that allows for more robust operation and significant expansion of achievable plasma parameters. The original plasma source made use of a heated barium oxide (BaO) coated nickel sheet as an electron emitter. This source had a number of drawbacks, including a limited range of plasma density (≲4.0 × 1012 cm−3), a limited discharge duration (∼10 ms), and susceptibility to poisoning following oxygen exposure. The new plasma source utilizes a 38 cm diameter lanthanum hexaboride (LaB6) cathode, which has a significantly higher emissivity, allowing for a much larger discharge power density, and is robust to exposure to air. Peak plasma density of up to 3.0 × 1013 cm−33 in helium gas has been achieved. The typical operating pressure is ∼10−5 Torr, while dynamic pressure can be achieved through the gas-puffing technique. Discharges as long as 70 ms have been produced, enabling a variety of long-time-scale studies of processes, such as turbulent particle transport. The new source has been in continuous operation for 14 months, having survived air leaks, power outages that led to rapid temperature changes on the cathode and heater, and planned machine openings. We describe the design, construction, and initial operation of this novel new large-area LaB6 plasma source.

Highly polarized positrons generated via few-PW lasers

Spin-polarized positron beams have widely been utilized in applications ranging from fundamental physical studies to material processing. Preparing highly polarized positron beams for accurate probing is a long-standing issue. Here, we put forward a method to produce ultra-relativistic polarized positrons with unprecedented purity in a femtosecond timescale employing a few-PW circularly polarized laser pulse. The fully spin-resolved QED Monte Carlo method is used for simulating the two successive QED processes during the interaction, i.e., nonlinear Compton scattering and nonlinear Breit–Wheeler pair production. As the photons emitted in a circularly polarized laser field are symmetrically polarized, the polarization of the intermediate gamma photon beam averages out to zero, which is advantageous for improving the polarization of positrons. Meanwhile, the moderate laser intensity suppresses the depolarization of the new-born positrons induced by radiation reaction effect. As a result, the polarization of the positrons can reach up to ≳ 90%, the highest among the laser-driven polarization schemes conceived hitherto. Furthermore, our method relaxes the requirement on laser intensity to few-PW level, offering a promising way of preparing polarized positrons with current-generation laser facilities.

Setup for the Ionic Lifetime Measurement of the 229mTh3+ Nuclear Clock Isomer

For the realization of an optical nuclear clock, the first isomeric excited state of thorium-229 (229mTh) is currently the only candidate due to its exceptionally low-lying excitation energy (8.338±0.024 eV). Such a nuclear clock holds promise not only to be a very precise metrological device but also to extend the knowledge of fundamental physics studies, such as dark matter research or variations in fundamental constants. Considerable progress was achieved in recent years in characterizing 229mTh from its first direct identification in 2016 to the only recent observation of the long-sought-after radiative decay channel. So far, nuclear resonance as the crucial parameter of a nuclear frequency standard has not yet been determined with laser-spectroscopic precision. To determine another yet unknown basic property of the thorium isomer and to further specify the linewidth of its ground-state transition, a measurement of the ionic lifetime of the isomer is in preparation. Theory and experimental investigations predict the lifetime to be 103–104 s. To precisely target this property using hyperfine structure spectroscopy, an experimental setup is currently being commissioned at LMU Munich. It is based on a cryogenic Paul trap providing long-enough storage times for 229mTh ions, that will be sympathetically cooled with 88Sr+. This article presents a concept for an ionic lifetime measurement and discusses the laser-optical part of a setup specifically developed for this purpose.

Observation of ultra-large Rabi splitting in the plasmon-exciton polaritons at room temperature

Abstract Modifying the light–matter interactions in the plasmonic structures and the two-dimensional (2D) materials not only advances the deeper understanding of the fundamental studies of many-body physics but also provides the opportunities for exploration of novel 2D plasmonic polaritonic devices. Here, we report the plasmon-exciton coupling in the hybrid system with a plasmonic metasurface which can confine the electric field in an extremely compact mode volume. Because of the 2D feature of the designed and fabricated Al plasmonic metasurface, the confined electronic field is distributed in the plane with the same orientation as that of the exciton dipole moment in the transition metal dichalcogenides monolayers. By finely tuning the geometric size of the plasmonic nanostructures, we can significantly modify the dispersion relation of the coupled plasmon and the exciton. Our system shows a strong coupling behavior with an achieved Rabi splitting up to ∼200 meV at room temperature, in ambient conditions. The effective tailoring of the plasmon-exciton coupling with the plasmonic metasurfaces provides the testing platform for studying the quantum electromagnetics at the subwavelength scale as well as exploring plasmonic polariton Bose–Einstein condensation at room temperature.

Nucleation and Growth of Bipyramidal Yb:LiYF4 Nanocrystals-Growing Up in a Hot Environment.

Lanthanide-doped LiYF4 (Ln:YLF) is commonly used for a broad variety of optical applications, such as lasing, photon upconversion and optical refrigeration. When synthesized as nanocrystals (NCs), this material is also of interest for biological applications and fundamental physical studies. Until now, it was unclear how Ln:YLF NCs grow from their ionic precursors into tetragonal NCs with a well-defined, bipyramidal shape and uniform dopant distribution. Here, we study the nucleation and growth of ytterbium-doped LiYF4 (Yb:YLF), as a template for general Ln:YLF NC syntheses. We show that the formation of bipyramidal Yb:YLF NCs is a multistep process starting with the formation of amorphous Yb:YLF spheres. Over time, these spheres grow via Ostwald ripening and crystallize, resulting in bipyramidal Yb:YLF NCs. We further show that prolonged heating of the NCs results in the degradation of the NCs, observed by the presence of large LiF cubes and small, irregular Yb:YLF NCs. Due to the similarity in chemical nature of all lanthanide ions our work sheds light on the formation stages of Ln:YLF NCs in general.

Probe microscopy is all you need * * Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published

We pose that microscopy offers an ideal real-world experimental environment for the development and deployment of active Bayesian and reinforcement learning methods. Indeed, the tremendous progress achieved by machine learning (ML) and artificial intelligence over the last decade has been largely achieved via the utilization of static data sets, from the paradigmatic MNIST to the bespoke corpora of text and image data used to train large models such as GPT3, DALL·E and others. However, it is now recognized that continuous, minute improvements to state-of-the-art do not necessarily translate to advances in real-world applications. We argue that a promising pathway for the development of ML methods is via the route of domain-specific deployable algorithms in areas such as electron and scanning probe microscopy and chemical imaging. This will benefit both fundamental physical studies and serve as a test bed for more complex autonomous systems such as robotics and manufacturing. Favorable environment characteristics of scanning and electron microscopy include low risk, extensive availability of domain-specific priors and rewards, relatively small effects of exogenous variables, and often the presence of both upstream first principles as well as downstream learnable physical models for both statics and dynamics. Recent developments in programmable interfaces, edge computing, and access to application programming interfaces (APIs) facilitating microscope control, all render the deployment of ML codes on operational microscopes straightforward. We discuss these considerations and hope that these arguments will lead to create novel set of development targets for the ML community by accelerating both real world ML applications and scientific progress.

Structured transverse orbital angular momentum probed by a levitated optomechanical sensor

The momentum carried by structured light fields exhibits a rich array of surprising features. In this work, we generate transverse orbital angular momentum (TOAM) in the interference field of two parallel and counter-propagating linearly-polarised focused beams, synthesising an array of identical handedness vortices carrying intrinsic TOAM. We explore this structured light field using an optomechanical sensor, consisting of an optically levitated silicon nanorod, whose rotation is a probe of the optical angular momentum, which generates an exceptionally large torque. This simple creation and direct observation of TOAM will have applications in studies of fundamental physics, the optical manipulation of matter and quantum optomechanics.

A stimulated Raman loss spectrometer for metrological studies of quadrupole lines of hydrogen isotopologues

We discuss layout and performance of a high-resolution Stimulated Raman Loss spectrometer that has been newly developed for accurate studies of spectral lineshapes and line centre frequencies of hydrogen isotopologues and in general of Raman active transitions. Thanks to the frequency comb calibration of the detuning between pump and Stokes lasers and to an active alignment of the two beams, the frequency accuracy is at a level of 50 kHz. Over the vertical axis the spectrometer benefits from shot-noise limited detection, signal enhancement via multipass cell, active flattening of the spectral baseline and measurement times of few seconds over spectral spans larger than 10 GHz. Under these conditions an efficient averaging of Raman spectra is possible over long measurement times with minimal distortion of spectral lineshapes. By changing the pump laser, transitions can be covered in a very broad frequency span, from 50 to 5000 cm−1, including both vibrational and rotational bands. The spectrometer has been developed for studies of fundamental and collisional physics of hydrogen isotopologues and has been recently applied to the metrology of the Q(1) 1–0 line of H2.