About

Tijana Rajh is a School Director and Professor at the School of Molecular Sciences at Arizona State University. She has extensive experience in the synthesis and study of colloidal semiconductor nanocrystals and their integration into hierarchical assemblies. Professor Rajh conducted some of the earliest research on quantum dots, a scientific area that has grown enormously and is of great current interest and impact. Her early studies involved electron transfer reactions and photoelectrochemistry of colloidal semiconductors and quantum dots, solar energy conversion into chemical fuels, and surface modification of nanocrystalline TiO2 nanoparticles for light-induced chemistries. She developed methods for seamless electronic integration of chelating ligands and colloidal semiconductors, creating hybrid properties between nanoparticles and organic molecules. Additionally, she applied magnetic resonance techniques to investigate spin effects during photoinduced electron transfer in hybrid structures and proposed the first method to control and initiate chemical reactions between semiconductor nanoparticles and biomolecules such as DNA strands and antibodies. Her current research focuses on developing self-adapting nanostructures for energy transduction, conversion, and storage, as well as hybrid systems for sensing biomolecules including quantum qubits. Professor Rajh earned her Ph.D. from the University of Belgrade, Serbia.

Research topics

• Photochemistry
• Optics
• Condensed matter physics
• Inorganic chemistry
• Organic chemistry
• Quantum mechanics
• Nanotechnology
• Materials science
• Physics
• Chemistry
• Physical chemistry
• Optoelectronics

Selected publications

• Exploring the Photogenerated Charge Transfer Mechanism in Cu ₂ O@MoS ₂ Heterojunction Photocatalyst Using Transient Absorption Spectroscopy

  ChemistrySelect · 2026-05-01

  articleOpen access

  ABSTRACT Both heterojunction and core–shell photocatalysts have demonstrated promising performance in photocatalytic CO 2 conversions to fuels. However, fundamental knowledge of heterojunctions in core–shell structures is highly desired to facilitate the design of future photocatalysts. By combining advanced experimental characterizations and density functional theory (DFT) calculations, the role of the Cu 2 O@MoS 2 heterojunction in photocatalytic CO 2 conversions to fuels was investigated. We discovered that the charge dynamics and electron transfer properties of Cu 2 O@MoS 2 photocatalysts are altered by the heterojunction and Cu 2 O underlayer due to the electron transfer from Cu 2 O to MoS 2 and the change in CO 2 adsorption strength on the hybrid catalyst surface. Consequently, more electrons can travel to the surrounding liquid environment to be consumed by CO 2 reduction. This study provides experimental and theoretical investigations of the fundamental mechanisms of heterojunction core–shell photocatalysts.

  PublisherDOI

• Tunable spin-phonon polarons in a chiral molecular qubit framework

  ArXiv.org · 2025-06-05

  preprintOpen access

  Chiral structures that produce asymmetric spin-phonon coupling can theoretically generate spin-phonon polarons -- quasiparticles exhibiting non-degenerate spin states with phonon displacements. These quasiparticles are speculated to be the origin of chirality-induced spin selectivity and presumably can display exotic dynamic behaviors. However, direct experimental evidence of spin-phonon polarons has been lacking. Using a chiral molecular qubit framework embedding stable semiquinone-like radicals, we report spin dynamic signatures that indicate the formation of spin-phonon polarons for the first time. Our non-adiabatic model reveals that these quasiparticles introduce an active spin relaxation channel when polaron reorganization energy approaches Zeeman splitting. This new channel manifests itself as anomalous, temperature-independent spin relaxation, which can be suppressed by high magnetic fields or pore-filling solvents (e.g. CH2Cl2, CS2). Such field- and guest-tunable relaxation is unattainable in conventional spin systems. Harnessing this mechanism could boost repetition rates in spin-based quantum information technologies without compromising coherence or quantum sensing performance.

  PublisherOA PDFDOI

• Residual charge dependence of spin transport in chiral biomolecules

  The Journal of Chemical Physics · 2025-11-03

  article

  Electron spin polarization in biomolecules has drawn significant attention as it embodies an unexplored mechanism for information propagation and electron transfer in biological systems. Despite extensive experimental and theoretical investigations of the CISS (Chirality-Induced Spin Selectivity), there are still many unanswered questions about how electrons are spin-polarized after passing through chiral molecules and, furthermore, how this process influences vital electron transfer reactions. Since peptides are excellent models to examine this aspect of the spin polarization phenomenon, calculations were carried out to compare the spin-dependent transport properties of a charge-neutral peptide composed of seven alanine residues (A7) to that containing a negatively charged aspartic acid residue (A6D), a positively charged lysine residue (A6K), and an aromatic tyrosine residue (A6Y). We focus our analysis on the spin polarization arising from both spinterface, that is, the interplay between the interfacial electric and magnetic dipole moments, and spin polarization induced by the CISS effect. We find that the asymmetry between the α and β spin transport channels is particularly pronounced in a peptide containing a tyrosine residue. Furthermore, the secondary structure of the peptide plays a key role in spin-dependent transport, with peptides possessing α-helical conformations exhibiting transmission higher than the corresponding extended structures. Tyrosine is a key molecular fragment in photosynthetic complexes and several other biological electron transfer systems. Our results indicate that the natural selection of tyrosine is linked to its versatile electronic structure that allows for a path to spin polarization, which in turn dramatically modifies the nature of electron transfer processes.

  PublisherDOI

• In-Depth Analysis of the Species and Transformations during Sol Gel-Assisted V₂PC Synthesis

  Inorganic Chemistry · 2024-05-24

  article

  The sol–gel reaction mechanism of 211 MAX phases has proven to be very complex when identifying the intermediate species, chemical processes, and conversions that occur from a mixture of metal salts and gelling agent into a crystalline ternary carbide. With mostly qualitative results in the literature (Cr2GaC, Cr2GeC, and V2GeC), additional analytical techniques, including thermal analysis, powder diffraction, total scattering, and various spectroscopic methods, are necessary to unravel the identity of the chemical compounds and transformations during the reaction. Here, we demonstrate the combination of these techniques to understand the details of the sol–gel synthesis of MAX phase V2PC. The metal phosphate complexes, as well as amorphous/nanocrystalline vanadium phosphate species (V in different oxidation states), are identified at all stages of the reaction and a full schematic of the reaction process is suggested. The early amorphous vanadium species undergo multiple changes of oxidation states while organic species decompose releasing a variety of small molecule gases. Amorphous oxides, analogous to [NH4][VO2][HPO4], V2PO4O, and VO2P2O7 are identified in the dried gel obtained during the early stages of the heating process (300 and 600 °C), respectively. They are carbothermally reduced starting at 900 °C and subsequently react to crystalline V2PC with the excess carbon in the reaction mixture. Through CHN analysis, we obtain an estimate of left-over amorphous carbon in the product which will guide future efforts of minimizing the amount of carbon in sol gel-produced MAX phases which is important for subsequent property studies.

  PublisherDOI

• Realizing solution-phase room temperature quantum coherence in a tetrathiafulvalene-based diradicaloid complex

  Cell Reports Physical Science · 2023-11-20 · 12 citations

  articleOpen access

  Molecular electron spins are promising candidates as scalable and tunable qubits but often suffer from undesirable decomposition pathways. Furthermore, significant spin-lattice relaxation and nuclear spin-mediated decoherence limit their applications. While advances in the synthesis of new molecular electron spin qubit candidates have led to improved coherence lifetimes, one key question is whether coherence can be maintained under conditions relevant for employment as quantum sensors. Here, we report a luminescent tetrathiafulvalene-based molecular qubit candidate with diradicaloid character centered on a nuclear-spin-free bridging ligand. This unique air- and water-stable scaffold exhibits a long electron spin decoherence time of hundreds of nanoseconds at ambient temperatures and in nuclear-spin-rich protonated solvents. These results distinguish this system as a promising candidate for the development of novel room temperature, solution-phase quantum sensing technologies and suggest that molecular electron spin qubits can be ideal candidates for these applications.

  PublisherDOI

• Semiconductor assisted metal deposition for nanolithography applications

  OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2023-01-23

  articleOpen access1st authorCorresponding

  An article of manufacture and method of forming nanoparticle sized material components. A semiconductor oxide substrate includes nanoparticles of semiconductor oxide. A modifier is deposited onto the nanoparticles, and a source of metal ions are deposited in association with the semiconductor and the modifier, the modifier enabling electronic hole scavenging and chelation of the metal ions. The metal ions and modifier are illuminated to cause reduction of the metal ions to metal onto the semiconductor nanoparticles.

  Publisher

• Light- and Chemical-Doping-Induced Magnetic Behavior of Eu Molecular Systems

  Inorganic Chemistry · 2023-07-28 · 5 citations

  articleOpen access1st authorCorresponding

  Variable temperature electron paramagnetic resonance (VT-EPR) was used to investigate the role of the environment and oxidation states of several coordinated Eu compounds. We find that while Eu(III) chelating complexes are diamagnetic, simple chemical reduction results in the formation of paramagnetic species. In agreement with the distorted D3h symmetry of Eu molecular complexes investigated in this study, the EPR spectrum of reduced complexes showed axially symmetric signals (g⊥ = 2.001 and g∥ = 1.994) that were successfully simulated with two Eu isotopes with nuclear spin 5/2 (151Eu and 153Eu with 48% and 52% natural abundance, respectively) and nuclear g-factors 151Eu/153Eu = 2.27. Illumination of water-soluble complex Eu(dipic)3 at 4 K led to the ligand-to-metal charge transfer (LMCT) that resulted in the formation of Eu(II) in a rhombic environment (gx = 2.006, gy = 1.995, gz = 1.988). The existence of LMCT affects the luminescence of Eu(dipic)3, and pre-reduction of the complex to Eu(II)(dipic)3 reversibly reduces red luminescence with the appearance of a weak CT blue luminescence. Furthermore, encapsulation of a large portion of the dipic ligand with Cucurbit[7]uril, a pumpkin-shaped macrocycle, inhibited ligand-to-metal charge transfer, preventing the formation of Eu(II) upon illumination.

  PublisherOA PDFDOI

• Formation of Carbon-Induced Nitrogen-Centered Radicals on Titanium Dioxide under Illumination

  JACS Au · 2023-11-27 · 12 citations

  articleOpen access

  Titanium dioxide is the most studied photocatalytic material and has been reported to be active for a wide range of reactions, including the oxidation of hydrocarbons and the reduction of nitrogen. However, the molecular-scale interactions between the titania photocatalyst and dinitrogen are still debated, particularly in the presence of hydrocarbons. Here, we used several spectroscopic and computational techniques to identify interactions among nitrogen, methanol, and titania under illumination. Electron paramagnetic resonance spectroscopy (EPR) allowed us to observe the formation of carbon radicals upon exposure to ultraviolet radiation. These carbon radicals are observed to transform into diazo- and nitrogen-centered radicals (e.g., CHxN2• and CHxNHy•) during photoreaction in nitrogen environment. In situ infrared (IR) spectroscopy under the same conditions revealed C–N stretching on titania. Furthermore, density functional theory (DFT) calculations revealed that nitrogen adsorption and the thermodynamic barrier to photocatalytic nitrogen fixation are significantly more favorable in the presence of hydroxymethyl or surface carbon. These results provide compelling evidence that carbon radicals formed from the photooxidation of hydrocarbons interact with dinitrogen and suggest that the role of carbon-based “hole scavengers” and the inertness of nitrogen atmospheres should be reevaluated in the field of photocatalysis.

  PublisherDOI

• Realizing Solution-Phase Room Temperature Quantum Coherence in a Tetrathiafulvalene-Based Diradicaloid Complex

  ChemRxiv · 2023-05-19 · 1 citations

  preprintOpen access

  Molecular electron spins are promising candidates as scalable and tunable qubits but often suffer from air sensitivity or other undesirable decomposition pathways. Furthermore, significant spin‒lattice relaxation and nuclear spin-mediated decoherence limit their applications. While significant advances in the synthesis of new molecular electron spin qubit candidates have led to improved coherence lifetimes, one key question is whether coherence can be maintained under conditions relevant for employment as quantum sensors, for instance in solution and at room temperature for sensing in biological systems. Here we report a tetrathiafulvalene-based molecular qubit candidate with spin centered on a nuclear spin-free bridging ligand. This unique air and water-stable scaffold exhibits a long spin decoherence time of hundreds of nanoseconds at ambient temperatures and in nuclear spin-rich protonated solvents. These results distinguish this system as a promising candidate for the development of novel room temperature, solution-phase quantum sensing technologies, and suggest that molecular electron spin qubits can be ideal candidates for these applications.

  PublisherOA PDFDOI

• Amplified spontaneous emission from europium-based molecular complexes coupled to photonic crystal cavities

  Applied Physics Letters · 2023-08-07 · 2 citations

  articleOpen access

  Rare-earth ion-based materials bear many remarkable optical properties that render them highly appealing for lighting and quantum-related applications. However, their small oscillator strength and weak emission often pose limitations. Here, we synthesize and couple Eu(III)-based molecular complexes to nanobeam photonic crystals supporting air modes. A reasonable spatial overlap between the molecular complexes and cavity modes leads to an average spontaneous emission coupling efficiency of 0.19. Our pump power-dependent photoluminescence measurements evidence amplified spontaneous emission from the molecular complexes with an amplification threshold as low as 4.4 W/cm2, likely benefiting from the efficient coupling. These findings suggest that integrating rare-earth ion-based molecular complexes with photonic structures could be a viable approach for regulating their emission characteristics for particular applications.

  PublisherOA PDFDOI

Frequent coauthors

• Nada M. Dimitrijević

  107 shared

• Marion C. Thurnauer

  Argonne National Laboratory

  40 shared

• Zoran Šaponjić

  Institute of General and Physical Chemistry

  38 shared

• Elena V. Shevchenko

  St Petersburg University

  36 shared

• Christopher S. Johnson

  30 shared

• Vladimiro Mújica

  Arizona State University

  28 shared

• Elena A. Rozhkova

  "National Medical Research Center for Rehabilitation and Balneology" of the Ministry of Health of the Russian Federation

  25 shared

• Kimberly A. Gray

  25 shared

Education

• Ph.D.

  University of Belgrade