Disentangling enantiosensitivity from dichroism using bichromatic fields

We discuss how tensorial observables, available in photoelectron angular distributions resulting from interaction between isotropic chiral samples and cross polarized $\omega$-$2\omega$ bichromatic fields, allow for chiral discrimination without chiral light and within the electric-dipole approximation. We extend the concept of chiral setup [Phys. Rev. A 98, 063428 (2018)], which explains how chiral discrimination can be achieved in the absence of chiral light, to the case of tensorial observables. We derive selection rules for the enantiosensitivity and dichroism of the $b_{l,m}$ coefficients describing the photoelectron angular distribution valid for both weak and strong fields and for arbitrary $\omega$-$2\omega$ relative phase. Explicit expressions for simple perturbative cases are given. We find that, besides the dichroic non-enantiosensitive [J. Chem. Phys. 151 074106 (2019)], and dichroic-and-enantiosensitive $b_{l,m}$ coefficients found recently [Phys. Rev. A 99, 063406 (2019)], there are also enantiosensitive non-dichroic $b_{l,m}$ coefficients. These reveal the molecular enantiomer independently of the relative phase between the two colors and are therefore observable even in the absence of stabilization of the $\omega$-$2\omega$ relative phase.Comment: 18 pages, 3 figure

On the molecular information revealed by photoelectron angular distributions of isotropic samples

We propose an alternative approach to the description and analysis of photoelectron angular distributions (PADs) resulting from isotropic samples in the case of few-photon absorption via electric fields of arbitrary polarization. As we demonstrate for the one- and two-photon cases, this approach reveals the molecular frame information encoded in the $b_{l,m}$ expansion coefficients of the PAD in a particularly clear way. Our approach does not rely on explicit partial wave expansions of the scattering wave function and the expressions we obtain are therefore interpreted in terms of the vector field structure of the photoionization dipole $\vec{D}(\vec{k})$ as a function of the photoelectron momentum $\vec{k}$. This provides very compact expressions that reveal how molecular rotational invariants couple to the setup (electric field polarization and detectors) rotational invariants. We rely heavily on this approach in a companion paper on tensorial chiral setups. Here we apply this approach to one-photon ionization and find that while $b_{0,0}$ depends only on the magnitude of $\vec{D}(\vec{k})$, $b_{1,0}$ (non-zero for chiral molecules) is sensitive only to the components of $\vec{D}(\vec{k})$ perpendicular to $\vec{k}$ encoded in the propensity field $\vec{B}(\vec{k})\equiv i\vec{D}^{*}(\vec{k})\times\vec{D}(\vec{k})$, and $b_{2,0}$ is sensitive only to the the component of $\vec{D}(\vec{k})$ along $\vec{k}$. We also analyze the resonantly enhanced two-photon case where we show that $b_{0,0}$ and $b_{1,0}$ can be written in terms of an effectively stretched $\vec{D}(\vec{k})$, and that $b_{1,0}$ and $b_{3,0}$ reveal structural information of the field $\vec{B}(\vec{k})$ encoded in three of its vector spherical harmonic expansion coefficients.Comment: 26 pages, 5 figure

Enantio-sensitive unidirectional light bending

Structured light, which exhibits nontrivial intensity, phase, and polarization patterns in space, has key applications ranging from imaging and 3D micromanipulation to classical and quantum communication. However, to date, its application to molecular chirality has been limited by the weakness of magnetic interactions. Here we structure light’s local handedness in space to introduce and realize an enantio-sensitive interferometer for efficient chiral recognition without magnetic interactions, which can be seen as an enantio-sensitive version of Young’s double slit experiment. Upon interaction with isotropic chiral media, such chirality-structured light effectively creates chiral emitters of opposite handedness, located at different positions in space. We show that if the distribution of light’s handedness breaks left-right symmetry, the interference of these chiral emitters leads to unidirectional bending of the emitted light, in opposite directions in media of opposite handedness, even if the number of the left-handed and right-handed emitters excited in the medium is exactly the same. Our work introduces the concepts of polarization of chirality and chirality-polarized light, exposes the immense potential of sculpting light’s local chirality, and offers novel opportunities for efficient chiral discrimination, enantio-sensitive optical molecular fingerprinting and imaging on ultrafast time scales

Effectiveness of rotavirus vaccination in Spain

With the aim of determining rotavirus vaccine effectiveness (RVVE) in Spain, from Oct-2008/Jun-2009, 467 consecutive children below 2 years old with acute gastroenteritis (AGE) were recruited using a pediatric research network (ReGALIP-www.regalip.org) that includes primary, emergency and hospital care settings. Of 467 enrolled children, 32.3% were rotavirus positive and 35.0% had received at least one dose of any rotavirus vaccine. RRVE to prevent any episode of rotavirus AGE was 91.5% (95% CI: 83.7%-95.6%). RVVE to prevent hospitalization by rotavirus AGE was 95.6% (85.6-98.6%). No differences in RVVE were found regarding the vaccine used. Rotavirus vaccines have showed an outstanding effectiveness in Spain