Metal L-edge Research Articles

The trials and triumphs of modelling X-ray absorption spectra of transition metal phthalocyanines.

This study explores the electronic structure of Co, Fe and Mn phthalocyanines (TMPcs) as well as their perfluorinated counterparts through a series of electronic structure calculations utilizing multireference methods and by simulating their metal L-edge and ligand (nitrogen and fluorine) K-edge X-ray absorption spectra (XAS) in an angle-resolved manner. Simulations targeting different ground-state symmetries, where relevant, have been conducted to observe changes in the N K-edge lineshape. The applicability of the quasi-degenerate formulation of n-electron valence state perturbation theory (QD-NEVPT2) for L-edge X-ray absorption spectroscopy (XAS) is evaluated, alongside the use of a restricted active space (RAS) formalism to describe the final-state multiplets generated by L-shell X-ray processes. Our findings provide valuable insights into the electronic properties of TMPcs, in particular with respect to the effect of fluorination, and demonstrate the broad applicability of various formulations of NEVPT2 in spectral simulations. Moreover, this study highlights the utility of manual truncation of the configuration spaces in order to allow for large active orbital spaces in aforementioned calculations.

Interpreting the Cu-O2 Antibonding Nature in Two Cu-O2 Complexes from Cu L-Edge X-ray Absorption Spectra.

Cu-O2 structures play important roles in bioinorganic chemistry and enzyme catalysis, where the bonding between the Cu and O2 parts serves as a fundamental research concern. Here, we performed a multiconfigurational study on the copper L2,3-edge X-ray absorption spectra (XAS) of two copper enzyme model complexes to gain a better understanding of the antibonding nature from the clearly interpreted structure-spectroscopy relation. We obtained spectra in good agreement with the experiments by using the restricted active space second-order perturbation theory (RASPT2) method, which facilitated reliable chemical analysis. Spectral feature interpretations were supported by computing the spin-orbit natural transition orbitals. All major features were assigned to be mainly from Cu 2p to antibonding orbitals between Cu 3d and O2 π*, Cu 3d-πO-O* (type A), and a few also to mixed antibonding/bonding orbitals between Cu 3d and O2 π, Cu 3d ± πO-O (type M). Our calculations provided a clear illustration of the interactions between Cu 3d and O2 π*/π orbitals that are carried in the metal L-edge XAS.

Synchrotron-based techniques for characterizing STCH water-splitting materials

Understanding the role of oxygen vacancy–induced atomic and electronic structural changes to complex metal oxides during water-splitting processes is paramount to advancing the field of solar thermochemical hydrogen production (STCH). The formulation and confirmation of a mechanism for these types of chemical reactions necessitate a multifaceted experimental approach, featuring advanced structural characterization methods. Synchrotron X-ray techniques are essential to the rapidly advancing field of STCH in part due to properties such as high brilliance, high coherence, and variable energy that provide sensitivity, resolution, and rapid data acquisition times required for the characterization of complex metal oxides during water-splitting cycles. X-ray diffraction (XRD) is commonly used for determining the structures and phase purity of new materials synthesized by solid-state techniques and monitoring the structural integrity of oxides during water-splitting processes (e.g., oxygen vacancy–induced lattice expansion). X-ray absorption spectroscopy (XAS) is an element-specific technique and is sensitive to local atomic and electronic changes encountered around metal coordination centers during redox. While in operando measurements are desirable, the experimental conditions required for such measurements (high temperatures, controlled oxygen partial pressures, and H2O) practically necessitate in situ measurements that do not meet all operating conditions or ex situ measurements. Here, we highlight the application of synchrotron X-ray scattering and spectroscopic techniques using both in situ and ex situ measurements, emphasizing the advantages and limitations of each method as they relate to water-splitting processes. The best practices are discussed for preparing quenched states of reduction and performing synchrotron measurements, which focus on XRD and XAS at soft (e.g., oxygen K-edge, transition metal L-edges, and lanthanide M-edges) and hard (e.g., transition metal K-edges and lanthanide L-edges) X-ray energies. The X-ray absorption spectra of these complex oxides are a convolution of multiple contributions with accurate interpretation being contingent on computational methods. The state-of-the-art methods are discussed that enable peak positions and intensities to be related to material electronic and structural properties. Through careful experimental design, these studies can elucidate complex structure–property relationships as they pertain to nonstoichiometric water splitting. A survey of modern approaches for the evaluation of water-splitting materials at synchrotron sources under various experimental conditions is provided, and available software for data analysis is discussed.

K-Edge and L-Edge Spectroscopy of Ni0.8Mn0.1Co0.1O2 Cathodes Under Expanded Voltage Conditions Via Soft X-Ray Absorption Spectroscopy

Mixed transition metal oxides, such as Ni0.8Mn0.1Co0.1O2 (NMC811), are intended to combine the high capacity of nickel oxides, the rate capability of cobalt oxides, and the structural stability of manganese oxides to meet the capacity and power demands of electric vehicles and commercial portable electronics. However, the capacity fade mechanisms in Ni-rich chemistries (x >y+z in NixMnyCozO2) can be elusive due to factors at the crystallographic, particle, or electrode level. In this study, bulk and surface x-ray spectroscopy characterization of NMC cathodes was used to explore cathode degradation mechanisms as influenced by cycling protocol, namely current rate and upper voltage limits. Soft x-ray absorption spectroscopy (sXAS) was used to probe the surface of recovered NMC electrodes via transition metal L-edge and O K-edge spectroscopy. The effect of rate and upper voltage potential under charge will be discussed to illustrate the versatility of sXAS for NMC cathode electrode characterization.

Direct and real-time observation of hole transport dynamics in anatase TiO2 using X-ray free-electron laser

Carrier dynamics affects photocatalytic systems, but direct and real-time observations in an element-specific and energy-level-specific manner are challenging. In this study, we demonstrate that the dynamics of photo-generated holes in metal oxides can be directly probed by using femtosecond X-ray absorption spectroscopy at an X-ray free-electron laser. We identify the energy level and life time of holes with a long life time (230 pico-seconds) in nano-crystal materials. We also observe that trapped holes show an energy distribution in the bandgap region with a formation time of 0.3 pico-seconds and a decay time of 8.0 pico-seconds at room temperature. We corroborate the dynamics of the electrons by using X-ray absorption spectroscopy at the metal L-edges in a consistent explanation with that of the holes.

Two-Component Multireference Restricted Active Space Configuration Interaction for the Computation of L-Edge X-ray Absorption Spectra.

X-ray absorption spectroscopy is a powerful probe of local electronic and nuclear structures, providing insights into chemical processes. The theoretical prediction and interpretation of metal L-edge X-ray absorption spectra are complicated by both relativistic effects, including spin-orbit coupling and the multiconfigurational nature of the states involved. This work details an exact two-component multireference restricted active space (RAS) configuration interaction scheme that uses an exact two-component state-averaged complete active space self-consistent-field method, which includes the spin-orbit coupling in a variational manner, for the accurate description of the electronic structure before using a RAS configuration interaction method to describe the core excited states of the X-ray spectrum. Benchmark calculations are presented for a series of iron-containing complexes, with results showing key features of the spectrum being reproduced, including ligand-to-metal charge transfer and shake-up excitations.

Attosecond state-resolved carrier motion in quantum materials probed by soft x-ray XANES

Recent developments in attosecond technology led to table-top x-ray spectroscopy in the soft x-ray range, thus uniting the element- and state-specificity of core-level x-ray absorption spectroscopy with the time resolution to follow electronic dynamics in real-time. We describe recent work in attosecond technology and investigations into materials such as Si, SiO2, GaN, Al2O3, Ti, and TiO2, enabled by the convergence of these two capabilities. We showcase the state-of-the-art on isolated attosecond soft x-ray pulses for x-ray absorption near-edge spectroscopy to observe the 3d-state dynamics of the semi-metal TiS2 with attosecond resolution at the Ti L-edge (460 eV). We describe how the element- and state-specificity at the transition metal L-edge of the quantum material allows us to unambiguously identify how and where the optical field influences charge carriers. This precision elucidates that the Ti:3d conduction band states are efficiently photo-doped to a density of 1.9 × 1021 cm−3. The light-field induces coherent motion of intra-band carriers across 38% of the first Brillouin zone. Lastly, we describe the prospects with such unambiguous real-time observation of carrier dynamics in specific bonding or anti-bonding states and speculate that such capability will bring unprecedented opportunities toward an engineered approach for designer materials with pre-defined properties and efficiency. Examples are composites of semiconductors and insulators like Si, Ge, SiO2, GaN, BN, and quantum materials like graphene, transition metal dichalcogens, or high-Tc superconductors like NbN or LaBaCuO. Exiting are prospects to scrutinize canonical questions in multi-body physics, such as whether the electrons or lattice trigger phase transitions.

The electronic structure and deexcitation pathways of an isolated metalloporphyrin ion resolved by metal L-edge spectroscopy.

The local electronic structure of the metal-active site and the deexcitation pathways of metalloporphyrins are crucial for numerous applications but difficult to access by commonly employed techniques. Here, we applied near-edge X-ray absorption mass spectrometry and quantum-mechanical restricted active space calculations to investigate the electronic structure of the metal-active site of the isolated cobalt(iii) protoporphyrin IX cation (CoPPIX+) and its deexcitation pathways upon resonant absorption at the cobalt L-edge. The experiments were carried out in the gas phase, thus allowing for control over the chemical state and molecular environment of the metalloporphyrin. The obtained mass spectra reveal that resonant excitations of CoPPIX+ at the cobalt L3-edge lead predominantly to the formation of the intact radical dication and doubly charged fragments through losses of charged and neutral side chains from the macrocycle. The comparison between experiment and theory shows that CoPPIX+ is in a 3A2g triplet ground state and that competing excitations to metal-centred non-bonding and antibonding σ* molecular orbitals lead to distinct deexcitation pathways.

Probing Depth-Dependent Transition-Metal Redox of Lithium Nickel, Manganese, and Cobalt Oxides in Li-Ion Batteries.

Layered lithium nickel, manganese, and cobalt oxides (NMC) are among the most promising commercial positive electrodes in the past decades. Understanding the detailed surface and bulk redox processes of Ni-rich NMC can provide useful insights into material design options to boost reversible capacity and cycle life. Both hard X-ray absorption (XAS) of metal K-edges and soft XAS of metal L-edges collected from charged LiNi0.6Mn0.2Co0.2O2 (NMC622) and LiNi0.8Mn0.1Co0.1O2 (NMC811) showed that the charge capacity up to removing ∼0.7 Li/f.u. was accompanied with Ni oxidation in bulk and near the surface (up to 100 nm). Of significance to note is that nickel oxidation is primarily responsible for the charge capacity of NMC622 and 811 up to similar lithium removal (∼0.7 Li/f.u.) albeit charged to different potentials, beyond which was followed by Ni reduction near the surface (up to 100 nm) due to oxygen release and electrolyte parasitic reactions. This observation points toward several new strategies to enhance reversible redox capacities of Ni-rich and/or Co-free electrodes for high-energy Li-ion batteries.

Post Mortem and Operando XPEEM: a Surface-Sensitive Tool for Studying Single Particles in Li-Ion Battery Composite Electrodes

X-ray photoemission electron microscopy (XPEEM), with its excellent spatial resolution, is a well-suited technique for elucidating the complex electrode-electrolyte interface reactions in Li-ion batteries. It provides element-specific contrast images that allows the study of the surface morphology and the identification of the various components of the composite electrode. It also enables the acquisition of local X-ray absorption spectra (XAS) on single particles of the electrode, such as the C and O K-edges to track the stability of carbonate-based electrolytes, F K-edge to study the electrolyte salt and binder stability, and the transition metal L-edges to gain insights into the oxidation/reduction processes of positive and negative active materials. Here we discuss the optimal measurement conditions for XPEEM studies of Li-ion battery systems, including (i) electrode preparation through mechanical pressing to reduce surface roughness for improved spatial resolution; (ii) corrections of the XAS spectra at the C K-edge to remove the carbon signal contribution originating from the X-ray optics; and (iii) procedures for minimizing the effect of beam damage. Examples from our recent work are provided to demonstrate the strength of XPEEM to solve challenging interface reaction mechanisms via post mortem measurements. Finally, we present a first XPEEM cell dedicated to operando/in situ experiments in all-solid-state batteries. Representative measurements were carried out on a graphite electrode cycled with LiI-incorporated sulfide-based electrolyte. This measurement demonstrates the strong competitive reactions between the lithiated graphite surface and the Li2O formation caused by the reaction of the intercalated lithium with the residual oxygen in the vacuum chamber. Moreover, we show the versatility of the operando XPEEM cell to investigate other active materials, for example, Li4Ti5O12.

Restricted active space simulations of the metal L-edge X-ray absorption spectra and resonant inelastic X-ray scattering: revisiting [CoII/III(bpy)3]2+/3+complexes

The metal L-edge spectra of cobalt compounds have been interpreted through restricted active space calculations.

Comparison of multireference ab initio wavefunction methodologies for X-ray absorption edges: A case study on [Fe(II/III)Cl4]2-/1- molecules.

In this work, we present a detailed comparison of wavefunction-based multireference (MR) techniques for the prediction of transition metal L-edge X-ray absorption spectroscopy (XAS) using [Fe(II)Cl4]2- and [Fe(III)Cl4]1- complexes as prototypical test cases. We focus on the comparison of MR Configuration Interaction (MRCI) and MR Equation of Motion Coupled Cluster (MREOM-CC) methods, which are employed to calculate valence excitation as well as core to valence Fe L-edge XAS spectra of [Fe(II)Cl4]2- and [Fe(III)Cl4]1- complexes. The two investigated approaches are thoroughly analyzed with respect to their information content regarding (1) metal-ligand covalency, (2) ligand field splittings, (3) relativistic effects, (4) electron correlation, (5) energy distribution, and (6) intensity modulation of the experimentally observed spectral features. It is shown that at the level of MRCI calculations in both [Fe(II)Cl4]2- and [Fe(III)Cl4]1- cases, very good agreement with the experimental Fe L-edge XAS spectra is obtained provided that the employed active space is extended to include ligand-based orbitals in addition to metal-based molecular orbitals. It is shown that this is necessary in order to correctly describe the important σ- and π- Fe-Cl covalent interactions. By contrast, MREOM-CC calculations yield excellent agreement relative to experiment even with small active spaces. The efficiency of the employed MR computational protocols is thoroughly discussed. Overall, we believe that this study serves as an important reference for future developments and applications of MR methods in the field of X-Ray spectroscopy.

Comparative Study on the Structural Degradation and Thermal Stability of LixNi0.5Co0.2Mn0.3O2 cathode Materials in Liquid and Solid Electrolyte Systems

Lithium-ion batteries (LIBs) using organic liquid electrolytes have been applied in portable devices such as laptops and cellular phones owing to its wide electrochemical stability, high voltages, and excellent energy density. LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode have attracted significant interest as the cathode materials for LIBs owing to their high capacity, excellent rate capability and low cost. NCM523 cathode materials have a disadvantage of structural instability, which caused by the reduction of Ni ions releases oxygen from the crystal structure at the high temeprature or high charged state, which can lead thermal runaway by reacting with the flammable electrolyte. The use of organic liquid electrolytes in LIBs raises safety issues due to its flammable character and the impact on the explosion is greater in particular for relatively large systems such as electrical vehicles and grid storage. To overcome the safety issues, solid state batteries (SSBs) using a non-combustible solid state Li-ion conductor are regarded as the realistic alternative to prohibit the leakage of liquid electrolytes and the resultant fire hazards. However, due to the large resistance in the electrode-electrolyte interface, the capacity retention and cycle effieciency of the SSBs become worse. Previous studies on SSBs have been mainly focused on developing solid state electrolytes with high ion conductivity. Despite growing interest in stability, the systematic studies of safety of SSBs depending on the type of electrolyte has never been evaluated so far. It is necessary for understanding structural deformations on the cathode material in the effects of the reactions beween the electrode and various types of electrolytes, which is essential for ensuring the safety of the batteries. In this study, we investigate the structural degradation and thermal stability on NCM523 cathode materials by taking an advantage of in situ transmission electron microscopy (TEM) in various electrolyte conditions, including conventional liquid electrolyte, poly(ethylene oxide) (PEO) complexes with LiClO4 (PEO-based solid electrolyte), and PEO/LiClO4/Li1.3Al0.3Ti1.7(PO4)3 (LATP) composite electrolyte (PEO-inorganic composite electrolyte). Since the LATP oxide electrolyte has brittleness and the PEO has flexibility, it adopts a composite electrolyte having inorganic and organic phases with good interface contact with the cell electrode. A cell composed of each electrolyte was prepared and charged with cut-off voltages of 3.9 V and 4.3 V at a rate of 0.05 C after the second formation process for stabilzing the cell. The capacity at the same cut-off voltage decreases in the order of conventional liquid electrolyte, PEO-based solid electrolyte, and PEO-inorganic composite electrolytes. To understand the thermal stability and the degradation mechanism, modifications in selected-area electron diffraction (SAED) and electron energy-loss (EEL) spectra of oxygen K-edge and transition metal (Ni, Co, Mn) L-edges of each of charged NCM523 cathode materials are monitored in real time at the range from room temperature to 300°C. Our work demonstrated that contact resistance at the interface between the electrode and electrolyte is important factor. This work provides important information on the relationship with structural deformation and thermal stability of the cathode materials, which is an essential part of the rational design to develope for high engergy densities and safe SSBs. All the details will be available at the meeting. Acknowledgement This work was supported by the Korea Institute of Science and Technology (KIST) Institutional Program (Project 2E28142). This work was also supported by the National Research Foundation of Korea (NRF) grant (No. 2018R1A2B2005205).

Fingerprinting Electronic Structure of Heme Iron by Ab Initio Modeling of Metal L-Edge X-ray Absorption Spectra.

The capability of the multiconfigurational restricted active space approach to identify electronic structure from spectral fingerprints is explored by applying it to iron L-edge X-ray absorption spectroscopy (XAS) of three heme systems that represent the limiting descriptions of iron in the Fe-O2 bond, ferrous and ferric [Fe(P)(ImH)2]0/1+ (P = porphine, ImH = imidazole), and FeII(P). The level of agreement between experimental and simulated spectral shapes is calculated using the cosine similarity, which gives a quantitative and unbiased assignment. Further dimensions in fingerprinting are obtained from the L-edge branching ratio, the integrated absorption intensity, and the edge position. The results show how accurate ab initio simulations of metal L-edge XAS can complement calculations of relative energies to identify unknown species in chemical reactions.

Ab initio calculation of ligand field multiplet parameters for transition metal L-edge spectra

A simple method for non-empirical ligand field multiplet calculations for transition metal L-edge spectra is presented. Ligand field splittings and anisotropic scaling factors for Coulomb integrals are obtained from density functional theory. The method is applied to transition metal monoxide solids and nickel and cobalt phthalocyanines molecules and good agreement with experiment is obtained.

Restricted Open-Shell Configuration Interaction Singles Study on M- and L-edge X-ray Absorption Spectroscopy of Solid Chemical Systems.

In this study the M- and L-edge X-ray absorption spectra of a series of open- and closed-shell solids (TiO2 rutile, α-Fe2O3 hematite, FeS2 pyrite, and the spinel Co3O4) are investigated with the restricted open-shell configuration interaction singles methods (ROCIS/DFT and PNO-ROCIS/DFT) using the embedded cluster approach. ROCIS/DFT type of methods are grounded in wave function-based ab initio electronic structure theory and have shown great performance in the field of X-ray spectroscopy in particular in the field of transition metal L-edge spectroscopy. In this work we show that ROCIS/DFT can be used to calculate and interpret metal M- and L-edge XAS spectra of solids. To this end, clusters with up to 52 metal centers are considered. In all cases good to excellent agreement between theory and experiment is obtained. The experimentally probed local coordination environments are discussed in detail. The physical origin of the observed spectral features is explored through the machinery of natural difference orbitals. This analysis provides valuable information with respect to the core to valence, metal to metal charge transfer, and metal to ligand charge transfer characters of the relativistically corrected many particle states. The influence of the above electronic effects to the spectral shapes and the size of the treated clusters are thoroughly investigated.

Direct Determination of Absolute Absorption Cross Sections at the L-Edge of Dilute Mn Complexes in Solution Using a Transmission Flatjet.

The 3d transition metals play a pivotal role in many charge transfer processes in catalysis and biology. X-ray absorption spectroscopy at the L-edge of metal sites probes metal 2p-3d excitations, providing key access to their valence electronic structure, which is crucial for understanding these processes. We report L-edge absorption spectra of MnII(acac)2 and MnIII(acac)3 complexes in solution, utilizing a liquid flatjet for X-ray absorption spectroscopy in transmission mode. With this, we derive absolute absorption cross-sections for the L-edge transitions with peak magnitudes as large as 12 and 9 Mb for MnII(acac)2 and MnIII(acac)3, respectively. We provide insight into the electronic structure with ab initio restricted active space calculations of these L-edge transitions, reproducing the experimental spectra with excellent agreement in terms of shapes, relative energies, and relative intensities for the two complexes. Crystal field multiplet theory is used to assign spectral features in terms of the electronic structure. Comparison to charge transfer multiplet calculations reveals the importance of charge transfer in the core-excited final states. On the basis of our experimental observations, we extrapolate the feasibility of 3d transition metal L-edge absorption spectroscopy using the liquid flatjet approach in probing highly dilute biological solution samples and possible extensions to table-top soft X-ray sources.

Probing the oxidation state of transition metal complexes: a case study on how charge and spin densities determine Mn L-edge X-ray absorption energies.

Transition metals in inorganic systems and metalloproteins can occur in different oxidation states, which makes them ideal redox-active catalysts. To gain a mechanistic understanding of the catalytic reactions, knowledge of the oxidation state of the active metals, ideally in operando, is therefore critical. L-edge X-ray absorption spectroscopy (XAS) is a powerful technique that is frequently used to infer the oxidation state via a distinct blue shift of L-edge absorption energies with increasing oxidation state. A unified description accounting for quantum-chemical notions whereupon oxidation does not occur locally on the metal but on the whole molecule and the basic understanding that L-edge XAS probes the electronic structure locally at the metal has been missing to date. Here we quantify how charge and spin densities change at the metal and throughout the molecule for both redox and core-excitation processes. We explain the origin of the L-edge XAS shift between the high-spin complexes MnII(acac)2 and MnIII(acac)3 as representative model systems and use ab initio theory to uncouple effects of oxidation-state changes from geometric effects. The shift reflects an increased electron affinity of MnIII in the core-excited states compared to the ground state due to a contraction of the Mn 3d shell upon core-excitation with accompanied changes in the classical Coulomb interactions. This new picture quantifies how the metal-centered core hole probes changes in formal oxidation state and encloses and substantiates earlier explanations. The approach is broadly applicable to mechanistic studies of redox-catalytic reactions in molecular systems where charge and spin localization/delocalization determine reaction pathways.

Depth-Dependent Redox Behavior of LiNi0.6Mn0.2Co0.2O2

Nickel-rich layered materials are emerging as cathodes of choice for next-generation high energy density lithium ion batteries intended for electric vehicles. This is because of their higher practical capacities compared to compositions with lower Ni content, as well as the potential for lower raw materials cost. The higher practical capacity of these materials comes at the expense of shorter cycle life, however, due to undesirable structure and chemical transformations, especially at particle surfaces. To understand these changes more fully, the charge compensation mechanism and bulk and surface structural changes of LiNi0.6Mn0.2Co0.2O2 were probed using synchrotron techniques and electron energy loss spectroscopy in this study. In the bulk, both the crystal and electronic structure changes are reversible upon cycling to high voltages, whereas particle surfaces undergo significant reduction and structural reconstruction. While Ni is the major contributor to charge compensation, Co and O (through transition metal-oxygen hybridization) are also redox active. An important finding from depth-dependent transition metal L-edge and O K-edge X-ray spectroscopy is that oxygen redox activity exhibits depth-dependent characteristics. This likely drives the structural and chemical transformations observed at particle surfaces in Ni-rich materials.

High-efficiency in situ resonant inelastic x-ray scattering (iRIXS) endstation at the Advanced Light Source.

An endstation with two high-efficiency soft x-ray spectrographs was developed at Beamline 8.0.1 of the Advanced Light Source, Lawrence Berkeley National Laboratory. The endstation is capable of performing soft x-ray absorption spectroscopy, emission spectroscopy, and, in particular, resonant inelastic soft x-ray scattering (RIXS). Two slit-less variable line-spacing grating spectrographs are installed at different detection geometries. The endstation covers the photon energy range from 80 to 1500 eV. For studying transition-metal oxides, the large detection energy window allows a simultaneous collection of x-ray emission spectra with energies ranging from the O K-edge to the Ni L-edge without moving any mechanical components. The record-high efficiency enables the recording of comprehensive two-dimensional RIXS maps with good statistics within a short acquisition time. By virtue of the large energy window and high throughput of the spectrographs, partial fluorescence yield and inverse partial fluorescence yield signals could be obtained for all transition metal L-edges including Mn. Moreover, the different geometries of these two spectrographs (parallel and perpendicular to the horizontal polarization of the beamline) provide contrasts in RIXS features with two different momentum transfers.