Asymmetric Spin Research Articles

Chiral Organometallic Complexes Derived from Helicenic N-Heterocyclic Carbenes (NHCs): Design, Structural Diversity, and Chiroptical and Photophysical Properties.

ConspectusRecently, helicene derivatives have emerged as an important class of molecules with potential applications spanning over asymmetric catalysis, biological activity, magnetism, spin filtering, solar cells, and polymer science. To harness their full potential, especially as emissive components in circularly polarized organic light-emitting diodes (CP-OLEDs), generating structural chemical diversity and understanding the resulting photophysical and chiroptical properties are crucial. In this Account, we shed light on chemical engineering combining helicene and N-heterocyclic carbene (NHC) chemistries to create transition-metal complexes with unique architectures and describe their photophysical and chiroptical attributes. The σ-donating and π-accepting capabilities of the helically chiral π-conjugated NHCs endow the complexes with remarkable structural and electronic features. These characteristics manifest in phenomena such as chirality induction, very long-lived phosphorescence, and strong chiroptical signatures (electronic circular dichroism and circularly polarized luminescence).We describe the different classes of ligands primarily developed in our group by classifying them according to their connection between the helicenic moiety and the imidazole precursor. This connection is essential in determining the degree of π-conjugation and characterizing the emissive state. We comprehensively discuss 6-coordinate, 4-coordinate, and 2-coordinate complexes, delving into their structural nuances and examining how the interplay between metals and auxiliary ligands shapes their photophysical properties, with interpretations enriched by DFT calculations. Helicenes are known to promote intersystem crossing thanks to strong spin-orbit coupling, while metals offer robust frameworks leading to a variety of molecular architectures with specific topologies together with distinct excited-state properties. The electronic configurations and energy levels of the ligand and metal orbitals thus significantly modulate the photophysical and chiroptical behaviors of these complexes. In-depth analysis of chiroptical properties, notably electronic circular dichroism and circularly polarized luminescence, emphasizes the influence of different stereogenic elements on the chiroptical responses across various energy ranges with appealing "match-mismatch" effects. Finally, we describe future prospects of helicene NHCs, particularly in the context of emerging research on cost-effective and abundant transition metals for materials science and for photocatalysis. Indeed, the inherent long-lived MLCT, excited-state delocalization, structural rigidity, and intrinsic chirality of these complexes present intriguing avenues for future investigations.

Asymmetric spin echo multi-echo echo planar imaging (ASEME-EPI) sequence for pre-clinical high-field fMRI.

In functional magnetic resonance imaging (fMRI) of the blood oxygen level-dependent (BOLD) contrast, gradient-recalled echo (GRE) acquisitions offer high sensitivity but suffer from susceptibility-induced signal loss and lack specificity to microvasculature. In contrast, spin echo (SE) acquisitions provide improved specificity at the cost of reduced sensitivity. This study introduces Asymmetric Spin Echo Multi-Echo Echo Planar Imaging (ASEME-EPI), a technique designed to combine the benefits of both GRE and SE for high-field preclinical fMRI. ASEME-EPI employs a spin echo readout followed by two asymmetric spin echo (ASE) GRE readouts, providing an initial T2-weighted SE image and subsequent T2 * -weighted ASE images. A feasibility study for the technique was implemented on a 9.4 T pre-clinical MRI system and tested using a visual stimulation in northern tree shrews. Comparing ASEME-EPI with conventional GRE echo planar imaging (GRE-EPI) and SE echo planar imaging (SE-EPI) acquisitions, results showed that ASEME-EPI achieved BOLD contrast-to-noise ratio (CNR) comparable to GRE-EPI while offering improved specificity in activation maps. ASEME-EPI activation was more confined to the primary visual cortex (V1), unlike GRE-EPI which showed activation extending beyond anatomical boundaries. Additionally, ASEME-EPI demonstrated the ability to recover signal in areas of severe field inhomogeneity where GRE-EPI suffered from signal loss. The performance of ASEME-EPI is attributed to its multi-echo nature, allowing for SNR-optimized combination of echoes, effectively denoising the data. The inclusion of the initial SE also contributes to signal recovery in areas prone to susceptibility artifacts. This feasibility study demonstrates the potential of ASEME-EPI for high-field pre-clinical fMRI, offering a promising compromise between GRE sensitivity and SE specificity while addressing challenges of T2 * decay at high field strengths.

Unveiling elevated curie temperature and exceptional perpendicular magnetic anisotropy in chlorinated monolayer CrI3

Due to the finite band gap and a ferromagnetic ground state, the CrI3 monolayer is attracting great research interests. However, the low Curie temperature of 46 K is one of the major obstacles for spintronics applications. Here, we have investigated the magnetic properties of chlorinated CrI3 monolayer with varying concentration of Cl. We investigated the dynamical and thermal stability by phonon dispersion and ab-initio molecular dynamic simulation. The band gap was decreasing with increasing Cl concentration and a half-metallic state is obtained at Cl concentration of 4.22 × 1014/cm2. The pristine CrI3 monolayer had perpendicular magnetic anisotropy energy of 0.84 meV/Cr. We find that this perpendicular magnetic anisotropy energy can be even enhanced twice by chlorination. Due to the hybridization of I and Cr atom, we found the spin asymmetric density of states in the iodine atom and this strong enhancement in the magnetic anisotropy originated from asymmetric spin features in iodine atom. We propose that the chlorination can increase the Curie temperature up to 204 K and this is almost four times enhanced value. Based on these finding, we propose that the chlorinated CrI3 system can be a promising material for spintronics applications.

Investigation of spin polarized semiconductor Cs2XMoBr6 (X = Li, Na) compounds for spintronic and optoelectronic applications

This study has applied the density functional theory (DFT) to calculate the structural, magnetoelectronic, optical, and thermoelectric characteristics of Cs2XMoBr6 (X = Li, Na). The magnetic stability of studied compounds is examined by minimizing their total ground state energies. Also, both compounds exhibit cubic stability by tolerance factor as well as negative enthalpy of formation. The analysis of spin-dependent electronic properties reveals the semiconductor nature of mentioned materials in both spin-up/dn versions. The computed Eg of 0.90/1.99 eV in spin-up/dn sections for Cs2NaMoBr6 while Cs2LiMoBr6 reveals Eg of 1.99/1.21 eV in spin-up/dn version. The optical properties show that incident light is optimally absorbed in visible to ultraviolet areas, indicating their potential use in UV-based photo sensors and other photovoltaic gadgets. The Mo-atom primarily participate to the total magnetic moment (μB(Tot)) for Cs2XMoBr6. Further, the material's high figure of merit (ZT) >0.7 within the 300 - 800 K temperature range for Cs2XMoBr6 indicate its high efficiency in thermoelectric (TE) applications. Semiconducting electronic bands with highly asymmetric spin polarization as well as greater TE efficiency, Cs2XMoBr6 materials are appropriate for uses in spintronics and energy harvesting.

Tunable spin splitting of reflected vortex-beam of Weyl semimetal metasurface with stronger optical activity

This work investigated the spin splitting of a reflected beam with a vortex beam irradiating on a metasurface. This metasurface structure is the periodically rectangular-groove array of ionic crystal, where the array is a sub-wavelength grating with its periodical direction situated in the surface plane. In the grating structure, we embedded magnetic Weyl semimetals. Consequently, a stronger optical activity can be found, which originates from the unique electronic structure of Weyl semimetals and the orientation of the grating arrangement. By controlling the separation of Weyl points and grating orientation, we observe notable asymmetric spin splitting in different frequency ranges with distinctly unique distributions. Significant spin splitting was observed to be correlated with substantial Kerr rotation angles and reflectance differences, indicating strong optical activity. Additionally, with the increasing topological charges, the spin splitting increases significantly. Our results are useful for the manipulation of infrared radiations and infrared optical detection.

A complexity trichotomy for k-regular asymmetric spin systems with complex edge functions

We prove a complexity trichotomy theorem for a class of partition functions over k-regular graphs, where the signature is complex valued and not necessarily symmetric. In details, we establish explicit criteria, according to which the partition functions of all such systems are classified into three classes: For every parameter setting in C for the spin system, the partition function is either (1) computable in polynomial time for every graph, or (2) #P-hard for general graphs but computable in polynomial time for planar graphs, or (3) #P-hard even for planar graphs.

Regulating Spin Density using TEMPOL Molecules for Enhanced CO2-to-Ethylene Conversion by HKUST-1 Framework Derived Electrocatalysts.

The selectivity of multicarbon products in the CO2 reduction reaction (CO2RR) depends on the spin alignment of neighboring active sites, which requires a spin catalyst that facilitates electron transfer with antiparallel spins for enhanced C-C coupling. Here, we design a radical-contained spin catalyst (TEMPOL@HKUST-1) to enhance CO2-to-ethylene conversion, in which spin-disordered (SDO) and spin-ordered (SO) phases co-exist to construct an asymmetric spin configuration of neighboring active sites. The replacement of axially coordinated H2O molecules with TEMPOL radicals introduces spin-spin interactions among the Cu(II) centers to form localized SO phases within the original H2O-mediated SDO phases. Therefore, TEMPOL@HKUST-1 derived catalyst exhibited an approximately two-fold enhancement in ethylene selectivity during the CO2RR at -1.8 V versus Ag/AgCl compared to pristine HKUST-1. In situ ATR-SEIRAS spectra indicate that the spin configuration at asymmetric SO/SDO sites significantly reduces the kinetic barrier for *CO intermediate dimerization toward the ethylene product. The performance of the spin catalyst is further improved by spin alignment under a magnetic field, resulting in a maximum ethylene selectivity of more than 50 %. The exploration of the spin-polarized kinetics of the CO2RR provides a promising path for the development of novel spin electrocatalysts with superior performance.

Goos–Hänchen shifts on spin representation

We analyze the Goos–Hänchen (GH) shift and longitudinal spin splitting (LSS) at a planar interface between two optical media in the spin representation. While these optical effects have been studied previously, we examine the direct and cross-reflected light fields, and their interference from the spin representation to reveal the physical mechanism of the GH shift and establish a quantitative relationship between it and LSS. Furthermore, we show that angular asymmetric spin splitting occurs under the spin representation when linearly polarized light with a phase difference of 180° and an amplitude ratio angle deviating from 45° impinges on the air–glass interface at Brewster’s angle. Finally, we reveal that the spin component field of the reflected light field for the total reflection case is different from that of the Brewster angle reflection, the most typical manifestation is that the intensity of the two spin component fields is not equal.

Giant asymmetric proximity-induced spin–orbit coupling in twisted graphene/SnTe heterostructure

We analyze the spin–orbit coupling effects in a 3∘-degree twisted bilayer heterostructure made of graphene and an in-plane ferroelectric SnTe, with the goal of transferring the spin–orbit coupling from SnTe to graphene, via the proximity effect. Our results indicate that the point-symmetry breaking due to the incompatible mutual symmetry of the twisted monolayers and a strong hybridization has a massive impact on the spin splitting in graphene close to the Dirac point, with the spin splitting values greater than 20 meV. The band structure and spin expectation values of graphene close to the Dirac point can be described using a symmetry-free model, triggering different types of interaction with respect to the threefold symmetric graphene/transition-metal dichalcogenide heterostructure. We show that the strong hybridization of the Dirac cone’s right movers with the SnTe band gives rise to a large asymmetric spin splitting in the momentum space. Furthermore, we discover that the ferroelectricity-induced Rashba spin–orbit coupling in graphene is the dominant contribution to the overall Rashba field, with the effective in-plane electric field that is almost aligned with the (in-plane) ferroelectricity direction of the SnTe monolayer. We also predict an anisotropy of the in-plane spin relaxation rates. Our results demonstrate that the group-IV monochalcogenides MX (M = Sn, Ge; X = S, Se, Te) are a viable alternative to transition-metal dichalcogenides for inducing strong spin–orbit coupling in graphene.

Super-resolution Deep Learning Reconstruction for 3D Brain MR Imaging: Improvement of Cranial Nerve Depiction and Interobserver Agreement in Evaluations of Neurovascular Conflict

Rationale and ObjectivesTo determine if super-resolution deep learning reconstruction (SR-DLR) improves the depiction of cranial nerves and interobserver agreement when assessing neurovascular conflict in 3D fast asymmetric spin echo (3D FASE) brain MR images, as compared to deep learning reconstruction (DLR). Materials and MethodsThis retrospective study involved reconstructing 3D FASE MR images of the brain for 37 patients using SR-DLR and DLR. Three blinded readers conducted qualitative image analyses, evaluating the degree of neurovascular conflict, structure depiction, sharpness, noise, and diagnostic acceptability. Quantitative analyses included measuring edge rise distance (ERD), edge rise slope (ERS), and full width at half maximum (FWHM) using the signal intensity profile along a linear region of interest across the center of the basilar artery. ResultsInterobserver agreement on the degree of neurovascular conflict of the facial nerve was generally higher with SR-DLR (0.429–0.923) compared to DLR (0.175–0.689). SR-DLR exhibited increased subjective image noise compared to DLR (p ≤ 0.008). However, all three readers found SR-DLR significantly superior in terms of sharpness (p < 0.001); cranial nerve depiction, particularly of facial and acoustic nerves, as well as the osseous spiral lamina (p < 0.001); and diagnostic acceptability (p ≤ 0.002). The FWHM (mm)/ERD (mm)/ERS (mm-1) for SR-DLR and DLR was 3.1–4.3/0.9–1.1/8,795.5–10,703.5 and 3.3–4.8/1.4–2.1/5,157.9–7,705.8, respectively, with SR-DLR's image sharpness being significantly superior (p ≤ 0.001). ConclusionsSR-DLR enhances image sharpness, leading to improved cranial nerve depiction and a tendency for greater interobserver agreement regarding facial nerve neurovascular conflict.

Asymmetric Magnon Frequency Comb.

We theoretically show the asymmetric spin wave transmission in a coupled waveguide-skyrmion structure, where the skyrmion acts as an effective nanocavity allowing the whispering gallery modes for magnons. The asymmetry originates from the chiral spin wave mode localized in the circular skyrmion wall. By inputting two-tone excitations and mixing them in the skyrmion wall, we observe a unidirectional output magnon frequency comb propagating in the waveguide with a record number of teeth (>50). This coupled waveguide-cavity structure turns out to be a universal paradigm for generating asymmetric magnon frequency combs, where the cavity can be generalized to other magnetic structures that support the whispering gallery mode of magnons. Our results advance the understanding of the nonlinear interaction between magnons and magnetic textures and open a new pathway to exploring the asymmetric spin wave transmission and to steering the magnon frequency comb.

Half-disturbed spin desalination: Asymmetric high-spin states in MnO2 accelerate charge transfer in capacitive deionization

Manganese dioxide (MnO2) has been recognized for its high theoretical capacitance. Recent advancements highlight the potential of modulating the spin state of Mn to elevate charge transfer kinetics. Nonetheless, the specific relationship between Mn spin distribution and desalination efficacy, alongside the underlying mechanism, remains elusive. This study introduces the novel concept of half-disturbed spin desalination, elucidating its complex mechanism via the strategic induction of oxygen vacancies on the MnO2 surface. Theoretical analyses reveal that electron transfer from the O py (up) and pz (up) to the Mn dz2 (up) orbitals alters MnO2's spin state from a symmetric low spin to an asymmetric high spin configuration. This transition disrupts spin up symmetry, bolstering dynamic processes and diminishing the ion diffusion energy barrier. Consequently, oxygen vacancy-enriched MnO2 (VO-MnO2) demonstrates an enhanced specific capacitance of 289 F g−1 at 1 A g−1. Remarkably, in the hybrid capacitive deionization (HCDI) process, it achieves a superior salt adsorption capacity (SAC) of 56.5 mg g−1 and a salt adsorption rate (SAR) of 2.5 mg g−1 min−1. This research pioneers the correlation between spin desalination mechanisms and spin state applications, paving the way for novel applications across diverse fields.

The structure, magnetism and mechanical properties of L21-type full-Heusler alloy Cr2ZrSi: A first-principles study

Heusler alloy is a widely studied spintronic material in recent years, which has played a huge role in the field of spintronic devices due to its high spin polarization and high Curie temperature. Using first-principles calculation to predict the basic properties of Heusler alloy can not only save experimental costs and time but also provide a reliable theoretical basis for experimental research. This study used a first-principles calculation to study the magnetic and mechanical properties of full-Heusler alloy Cr2ZrSi with an L21-type structure. The research results indicate that the alloy is a half-metallic ferromagnetic material with a theoretical value of 100% spin polarization. The magnetism mainly comes from the asymmetric spin contribution of d-orbital electrons of transition metal atoms and their hybridization. At the same time, this complex hybridization coupling process is also a possible reason for the half-metallic band gaps. In terms of mechanical properties, the Cr2ZrSi alloy exhibits good ductility and anisotropy, with a Debye temperature of 303.848K. Our theoretical research results provide more choices and theoretical basis for subsequent experimental research.

Regulating Spin Density using TEMPOL Molecules for Enhanced CO2‐to‐Ethylene Conversion by HKUST‐1 Framework Derived Electrocatalysts

The selectivity of multicarbon products in the CO2 reduction reaction (CO2RR) depends on the spin alignment of neighboring active sites, which requires a spin catalyst that facilitates electron transfer with antiparallel spins for enhanced C‐C coupling. Here, we design a radical‐contained spin catalyst (TEMPOL@HKUST‐1) to enhance CO2‐to‐ethylene conversion, in which spin‐disordered (SDO) and spin‐ordered (SO) phases co‐exist to construct an asymmetric spin configuration of neighboring active sites. The replacement of axially coordinated H2O molecules with TEMPOL radicals introduces spin‐spin interactions among the Cu(II) centers to form localized SO phases within the original H2O‐mediated SDO phases. Therefore, TEMPOL@HKUST‐1 derived catalyst exhibited an approximately two‐fold enhancement in ethylene selectivity during the CO2RR at ‐1.8 V versus Ag/AgCl compared to pristine HKUST‐1. In situ ATR‐SEIRAS spectra indicate that the spin configuration at asymmetric SO/SDO sites significantly reduces the kinetic barrier for *CO intermediate dimerization toward the ethylene product. The performance of the spin catalyst is further improved by spin alignment under a magnetic field, resulting in a maximum ethylene selectivity of more than 50%. The exploration of the spin‐polarized kinetics of the CO2RR provides a promising path for the development of novel spin electrocatalysts with superior performance.

Tunable spatial and angular spin splitting of reflected vortex-beam off hyperbolic metasurface

This paper investigated the spin splitting of the reflected beam with a vortex beam irradiating on a hyperbolic metasurface. This metasurface structure is the periodically rectangular-groove array on the surface of a hyperbolic crystal with the optical axis normal to its surface, where the array is a sub-wavelength biaxially hyperbolic grating with its periodical direction situated in the surface plane. Based on the hexagonal nitride boron crystal, we theoretically and numerically analyzed the spatial and angular spin splittings of the reflected beam, containing those produced by the transverse and longitudinal shifts. We found that the spatial shifts or spin splitting can be obtained in the first-order approximation of beam deflection, but the angular shifts can be described in the second-order approximation so that it enormously varies with the beam waist. Due to the hyperbolic anisotropy of the metasurface and the intrinsic orbital angular momentum in the incident beam, the expressions of spatial and angular shifts are effectively modified, and a unique double reflection effect occurs on the surface. Near certain reflective intensity distribution singularities, extremely asymmetrical spin splitting can be observed. These shifts and spin splitting can be tuned by varying the orientation of the incident plane and the angle of incidence.

Active manipulation of the plasmonic induced asymmetric photonic spin Hall effect

The asymmetric photonic spin Hall effect (APSHE) induced by surface plasmon polaritons in a graphene-based structure is actively manipulated by external magnetic field and electric field. It is revealed that the spin-dependent splitting exhibits spatio-temporal asymmetric property due to the involvement of the anisotropic graphene. The peak of asymmetry degree in APSHE at the position of reflectance valley corresponds toward a smaller incident angle with the increase of magnetic field intensity or Fermi energy, which is attributed to the tunability of reflectance for the graphene-based structure. Based on the asymmetric splitting shift, a potential application is proposed for detecting low concentration gas molecules and the detection resolution can be dynamically tunable by changing the magnetic field intensity and Fermi energy. This study may provide a new reference in the fabrication of graphene-based plasmonic sensor devices.

Evaluation of renal tubular function by multiparametric functional MRI in early diabetes

PurposeTo evaluate the tubular function in an alloxan-induced type 1 diabetes mellitus (DM) rabbit model measured by renal oxygenation (R2*), oxygen extraction fraction (OEF), and renal blood flow (RBF) using blood oxygenation level dependent, asymmetric spin echo, and arterial spin labeling MRI.MethodsTwenty-six rabbits were randomized into the 3-day DM group (n = 13) and the 7-day DM group (n = 13). We performed pairs of multiparametric MRIs (before and after furosemide injection) at baseline and 3/7 days post-DM, and scored pathological kidney injury. We performed statistical analyses using non-parametric, chi-square, and Spearman correlation tests.ResultsAt baseline, medullary R2* significantly decreased by 24.97% and 16.74% in the outer and inner stripes of the outer medulla (OS and IS, p = 0.006 and 0.003, respectively) after furosemide administration. While the corresponding OEF decreased by 15.91% for OS and 16.67% for IS (both p = 0.003), and no significant change in medullary RBF was observed (p > 0.05). In the 3-day DM group, the decrease of medullary R2* and OEF post-furosemide became unremarkable, suggesting tubular dysfunction. We noticed similar changes in the 7-day DM group. Correlation analysis showed pathological tubular injury score significantly correlated with medullary ∆R2* (post-furosemide – pre-furosemide difference, r = 0.82 for OS and 0.82 for IS) and ∆OEF (r = 0.82 for OS and 0.82 for IS) (p < 0.001, respectively).Conclusion: The combination of medullary OEF and R2* in response to furosemide could detect renal tubular dysfunction in early DM.

Longitudinally continuous varying high-order cylindrical vector fields enabled by spin-decoupled metasurfaces

Abstract The manipulation of vector optical fields in three-dimensional (3D) space plays a vital role in both fundamental research and practical implementations of polarization optics. However, existing studies mostly focus on 3D vector optical fields with limited modes. Here, an approach of spin-decoupled spatial partitioning is proposed to generate complex 3D vector optical fields with a customizable number of modes on demand. The crosstalk among different modes is effectively suppressed by the decoupling capability of asymmetric photonic spin–orbit interactions (PSOIs) and the design of region displacement for opposite spin states. As a proof-of-concept demonstration, a metasurface is designed to generate longitudinally varying high-order cylindrical vector fields, ranging from the 2nd to the 10th order in even sequences along the propagation direction. The experimental results demonstrate the effectiveness and potential of our approach to enabling precise control of 3D vector optical fields with arbitrary mode combinations. This work holds promising applications in biophotonics, quantum optics, and communications.

Comparison of cerebral oxygen extraction fraction using ASE and TRUST methods in patients with sickle cell disease and healthy controls

Abnormal oxygen extraction fraction (OEF), a putative biomarker of cerebral metabolic stress, may indicate compromised oxygen delivery and ischemic vulnerability in patients with sickle cell disease (SCD). Elevated OEF was observed at the tissue level across the brain using an asymmetric spin echo (ASE) MR method, while variable global OEFs were found from the superior sagittal sinus (SSS) using a T2-relaxation-under-spin-tagging (TRUST) MRI method with different calibration models. In this study, we aimed to compare the average ASE-OEF in the SSS drainage territory and TRUST-OEF in the SSS from the same SCD patients and healthy controls. 74 participants (SCD: N = 49; controls: N = 25) underwent brain MRI. TRUST-OEF was quantified using the Lu-bovine, Bush-HbA and Li-Bush-HbS models. ASE-OEF and TRUST-OEF were significantly associated in healthy controls after controlling for hematocrit using the Lu-bovine or the Bush-HbA model. However, no association was found between ASE-OEF and TRUST-OEF in patients with SCD using either the Bush-HbA or the Li-Bush-HbS model. Plausible explanations include a discordance between spatially volume-averaged oxygenation brain tissue and flow-weighted volume-averaged oxygenation in SSS or sub-optimal calibration in SCD. Further work is needed to refine and validate non-invasive MR OEF measurements in SCD.

Abstract TMP10: Children With Sickle Cell Anemia Have Impaired Cerebrovascular Reactivity

Introduction: Sickle Cell Anemia (SCA) causes lower hemoglobin, leading to increased cerebral blood flow (CBF) to maintain cerebral oxygen metabolism (CMRO 2 ). Although CBF rises in childhood to meet higher CMRO 2 demands, further compensatory increases in CBF in children with SCA may tap into a limited hemodynamic reserve, increasing risk for infarct. Cerebrovascular reactivity (CVR) reflects hemodynamic reserve by measuring the vasculature’s response to vasoactive stimuli, particularly in the gray matter (GM). We hypothesized that children with SCA have lower GM CVR, regardless of CMRO 2 . Methods: We used magnetic resonance imaging of children with and without SCA to collect pseudocontinuous arterial spin labeling (pCASL) for CBF, asymmetric spin echo for oxygen extraction fraction (OEF) and blood oxygen level dependent (BOLD) data correlated with hypercapnic challenges for CVR. Lab draws confirmed Hemoglobin (Hb) values. CMRO 2 was calculated as CBF x OEF x Arterial Oxygen Content (1.36 x Hb x SpO 2 ). Continuous variable differences between groups were analyzed using the Mann-Whitney U test, and categorical variables using the Fisher’s exact test. Linear regression assessed the relationship between CVR and Hb. Reported significant relationships survived multiple comparisons correction. Results: A total of 35 participants, ages 8–22 years had quality CVR data [9 SCA subjects (5 male) and 26 controls (9 male)]. Of these, 8 SCA and 20 controls had adequate quality metabolic data. The groups are matched by age (p=0.56) and sex (p=0.43). Children with SCA had higher GM CBF (62.0 v 49.3 mL/100g/min; p=0.03), but similar GM CMRO 2 (1.81 v 1.42 mL/100g/min; p=0.07) than controls. GM CVR was significantly lower in SCA than controls (0.17 v 0.27 %/mmHg; p=0.0003). Lower CVR was associated with lower Hb (Figure) after adjusting for age and sex (p &lt;0.0001). Conclusion: Lower GM CVR in children with SCA indicates a lower hemodynamic reserve, likely related to the degree of anemia.