The simplest molecules in nature, molecular hydrogen ions in the form of H2(+) and HD(+), provide an important benchmark system for tests of quantum electrodynamics in complex forms of matter. Here, ...we report on such a test based on a frequency measurement of a vibrational overtone transition in HD(+) by laser spectroscopy. We find that the theoretical and experimental frequencies are equal to within 0.6(1.1) parts per billion, which represents the most stringent test of molecular theory so far. Our measurement not only confirms the validity of high-order quantum electrodynamics in molecules, but also enables the long predicted determination of the proton-to-electron mass ratio from a molecular system, as well as improved constraints on hypothetical fifth forces and compactified higher dimensions at the molecular scale. With the perspective of comparisons between theory and experiment at the 0.01 part-per-billion level, our work demonstrates the potential of molecular hydrogen ions as a probe of fundamental physical constants and laws.
Extreme ultraviolet (EUV) lithography is currently entering high-volume manufacturing to enable the continued miniaturization of semiconductor devices. The required EUV light, at 13.5 nm wavelength, ...is produced in a hot and dense laser-driven tin plasma. The atomic origins of this light are demonstrably poorly understood. Here we calculate detailed tin opacity spectra using the Los Alamos atomic physics suite ATOMIC and validate these calculations with experimental comparisons. Our key finding is that EUV light largely originates from transitions between multiply-excited states, and not from the singly-excited states decaying to the ground state as is the current paradigm. Moreover, we find that transitions between these multiply-excited states also contribute in the same narrow window around 13.5 nm as those originating from singly-excited states, and this striking property holds over a wide range of charge states. We thus reveal the doubly magic behavior of tin and the origins of the EUV light.
Accurate investigations of quantum-level energies in molecular systems are shown to provide a testing ground to constrain the size of compactified extra dimensions. This is made possible by recent ...progress in precision metrology with ultrastable lasers on energy levels in neutral molecular hydrogen (H2, HD, and D2) and molecular hydrogen ions (H2+, HD+, and D2+). Comparisons between experiment and quantum electrodynamics calculations for these molecular systems can be interpreted in terms of probing large extra dimensions, under which conditions gravity will become much stronger. Molecules are a probe of spacetime geometry at typical distances where chemical bonds are effective (i.e., at length scales of an ). Constraints on compactification radii for extra dimensions are derived within the Arkani-Hamed-Dimopoulos-Dvali framework, while constraints for curvature or brane separation are derived within the Randall-Sundrum framework. Based on the molecular spectroscopy of D2 molecules and HD+ ions, the compactification size for seven extra dimensions (in connection to M-theory defined in 11 dimensions) of equal size is shown to be limited to . While limits on compactification sizes of extra dimensions based on other branches of physics are compared, the prospect of further tightening constraints from the molecular method is discussed.
We report on the discovery of a high-velocity narrow absorption line outflow in the redshift 2.3 quasar J212329.46 − 005052.9. Five distinct outflow systems are detected with velocity shifts from ...−9710 to −14 050 km s−1 and C iv λλ1548, 1551 linewidths of FWHM ≈ 62-164 km s−1. This outflow is remarkable for having high speeds and a degree of ionization similar to broad absorption line (BAL) flows, but linewidths roughly 100 times narrower than BALs and no apparent X-ray absorption. This is also, to our knowledge, the highest-velocity narrow absorption line system confirmed to be in a quasar outflow by all three indicators of line variability, smooth superthermal line profiles and doublet ratios that require partial covering of the quasar continuum source. All five systems have stronger absorption in O vi λλ1032, 1038 than C iv with no lower ionization metal lines detected. Their line variabilities also appear coordinated, with each system showing larger changes in C iv than O vi and line strength variations accompanied by nearly commensurate changes in the absorber covering fractions. The metallicity is approximately twice solar.
These data require five distinct outflow structures with similar kinematics, physical conditions and characteristic sizes of order 0.01-0.02 pc (based on partial covering). The coordinated line variations, occurring on time-scales ≤0.63 yr (quasar frame), are best explained by global changes in the outflow ionization caused by changes in the quasar's ionizing flux. An upper limit on the acceleration, ≲3 km s−1 yr−1, is consistent with blobs of gas that are gravitationally unbound and coasting freely ≳5 pc from the central black hole. Additional constraints from the variability time indicate that the full range of plausible distances is 5 ≲ R ≲ 1100 pc. However, if these small absorbing structures were created in the inner flow, they should be near the ∼5 pc minimum radius because they can travel just a few pc before dissipating (without external confinement). An apparent double line-lock in C iv suggests that the flow was radiatively accelerated and its present trajectory is within ∼16° of the radial (line-of-sight) direction. The absence of strong X-ray absorption shows that radiative shielding in the far-UV and X-rays is not needed to maintain moderate BAL-like ionizations and therefore, apparently, it is not needed to facilitate the radiative acceleration to high speeds. We argue that the ionization is moderated, instead, by high gas densities in small outflow substructures. Finally, we estimate that the kinetic energy yield from this outflow is at least 2 orders of magnitude too low to be important for feedback to the host galaxy's evolution.
Nuclear-spin-symmetry conservation makes the observation of transitions between quantum states of ortho- and para-H2 extremely challenging. Consequently, the energy-level structure of H2 derived from ...experiment consists of two disjoint sets of level energies, one for para-H2 and the other for ortho-H2. We use a new measurement of the ionization energy of para-H2 EI(H2)/(hc)=124 417.491 098(31) cm−1 to determine the energy separation 118.486 770(50) cm−1 between the ground states of para- and ortho-H2 and thus link the energy-level structure of the two nuclear-spin isomers of this fundamental molecule. Comparison with recent theoretical results M. Puchalski et al., Phys. Rev. Lett. 122, 103003 (2019) enables the derivation of an upper bound of 1.5 MHz for a hypothetical global shift of the energy-level structure of ortho-H2 with respect to that of para-H2.
Weak transitions in the (2,0) overtone band of the hydrogen deuteride molecule at λ=1.38 μm were measured in saturated absorption using the technique of noise-immune cavity-enhanced optical ...heterodyne molecular spectroscopy. Narrow Doppler-free lines were interrogated with a spectroscopy laser locked to a frequency comb laser referenced to an atomic clock to yield transition frequencies R(1)=217105181895(20) kHz; R(2)=219042856621(28) kHz; R(3)=220704304951(28) kHz at three orders of magnitude improved accuracy. These benchmark values provide a test of QED in the smallest neutral molecule, and they open up an avenue to resolve the proton radius puzzle, as well as constrain putative fifth forces and extra dimensions.
The hydrogen molecule has become a test ground for quantum electrodynamical calculations in molecules. Expanding beyond studies on stable hydrogenic species to the heavier radioactive tritium-bearing ...molecules, we report on a measurement of the fundamental T2 vibrational splitting (v=0→1) for J=0–5 rotational levels. Precision frequency metrology is performed with high-resolution coherent anti-Stokes Raman spectroscopy at an experimental uncertainty of 10–12 MHz, where sub-Doppler saturation features are exploited for the strongest transition. The achieved accuracy corresponds to a 50-fold improvement over a previous measurement, and it allows for the extraction of relativistic and QED contributions to T2 transition energies.
PDF
