Shaanxi Normal University, 

China

Xi 'an Institute of Optics and 

Precision Mechanics, CAS, 

China

Politecnico di Milano, Italy

Max Born Institute, Germany

California Institute of 

Technology, USA

Shanghai Jiao Tong University,

 China

Yu Fang

Shaanxi Normal University, China

ABSTRACT

Film-based Fluorescent Sensors (FFSs) are a critical solution for developing high-performance sensors capable of detecting hazardous, toxic, and harmful chemicals, biological substances, radioactive materials, as well as strain, stress, humidity, and other parameters. By examining key factors such as mass transfer, energy transfer, microenvironment effects, sensing unit utilization efficiency, the photochemical stability of sensing materials, and moisture/dust barrier materials—all of which significantly influence FFS performance—we highlight the essential role of innovation in sensing and barrier materials. This includes advancements in sensing unit design and synthesis, modulation of excited-state processes, optimization of adlayer structures, and internal structural tuning of barrier materials. Additionally, we explore innovations in sensor hardware architecture and improvements in detection equipment. Based on these insights, we assess the future development prospects and major challenges for FFSs.

For details, see our review papers published recently: (1) Yan Luo, Xiaoyan Liu, Yu Fang. Acc. Mater. Res. 2025, 6, 5, 600; (2) Rongrong Huang, Taihong Liu, Haonan Peng, Jing Liu, Xiaogang Liu, Liping Ding, Yu Fang. Chem. Soc. Rev. 2024, 53, 6960.

Mauro Nisoli

Politecnico di Milano, Italy

ABSTRACT

Photoinduced charge transfer (CT) is a fundamental process underpinning a wide range of phenomena in both natural and engineered systems. Despite significant advancements in ultrafast spectroscopy, the elementary mechanisms governing the initial stages of CT remain incompletely understood. A major challenge lies in capturing the complex coupling between electronic and nuclear degrees of freedom that emerges immediately after photoexcitation. Elucidating these ultrafast dynamics is critical not only for advancing fundamental knowledge but also for enabling innovation in optoelectronic and molecular electronic technologies. Ultrafast CT can be initiated either by attosecond extreme ultraviolet (EUV) pulses, which induce photoionization and permit tracking of electronic motion in molecular ions, or by few-cycle ultraviolet (UV) pulses, which maintain the molecule in a neutral state. Achieving femtosecond or sub-femtosecond resolution in the latter case requires UV pulses confined to only a few optical cycles.

This work employs both approaches in a complementary fashion. Using attosecond EUV-IR photoion spectroscopy, we examine a model donor–acceptor system to resolve the structural dependence of charge dynamics. Our findings reveal that CT does not proceed via continuous electron flow but initiates with a prompt redistribution of electron density, characterized by oscillatory behavior linked to nuclear motion. Additionally, we present a cutting-edge beamline designed for time-resolved photoelectron spectroscopy, featuring sub-3 fs tunable UV pump pulses and attosecond probe pulses. This setup enables high-resolution studies of ultrafast electronic processes, including nonadiabatic transitions and vibronic coupling, providing unprecedented insight into the interplay between electronic structure and nuclear rearrangements.

BIOGRAPHY

Mauro Nisoli is Full Professor at Politecnico di Milano since 2011. He leads the Attosecond Research Center within the Department of Physics of Politecnico and serves as co-director of the international school The Frontiers of Attosecond and Ultrafast X-ray Science. He is the author of over 230 peer-reviewed publications in international journals and has delivered numerous invited talks and tutorials at leading international conferences and schools. He was awarded an ERC Advanced Grant in 2009 (Electron-scale dynamics in chemistry, ELYCHE) and an ERC Synergy Grant in 2020 (The Ultimate Time Scale in Organic Molecular Opto-Electronics, the Attosecond, TOMATTO). In 2019, he was named OSA Fellow for his innovative contributions to attosecond science and technology, particularly for pioneering applications of attosecond pulses to molecular systems.

He has made groundbreaking contributions to attosecond science, especially in ultrafast electron dynamics in molecules and condensed matter. He co-invented the hollow-fiber compression technique, which enables few-cycle laser pulses at millijoule energies, now a global standard for generating isolated attosecond pulses. In 2006, his group achieved the first complete temporal characterization of isolated attosecond pulses, and in 2010 he developed an advanced temporal gating technique to produce high-energy isolated attosecond pulses. A pioneer in attochemistry, Nisoli performed the first attosecond pump-probe experiment on H2 and D2 in 2010. In 2014, he extended these studies to amino acids, achieving the first experimental observation of charge migration in complex molecules. Most recently, in 2024, he investigated the earliest stages of charge transfer in donor–acceptor systems, uncovering the fundamental coupling between ultrafast electronic redistribution and structural dynamics.

Marc Vrakking

Max Born Institute, Germany

ABSTRACT

Attosecond pulses produced using high-harmonic generation (HHG) have photon energies in the extreme-ultraviolet (XUV) and soft x-ray regime. As such, these pulses are ionizing radiation for any sample (atomic, molecular, liquid, solid) placed in their path. In attosecond pump-probe experiments, the time-resolved dynamics under investigation is commonly associated with either the photoelectrons (e.g. in measurements of photoionization time delays) or located within the ions (e.g. in observations of so-called “charge migration”). However, the observable dynamics may be compromised by quantum entanglement between the ions and photoelectrons.

We have investigated, both experimentally and theoretically, the role of ion-photoelectron entanglement in attosecond pump-probe probe scenarios relying on the creation of vibrational, respectively electronic coherence in H2+ ions that are produced via attosecond ionization of H2. In the former experiments, we could show that the degree of vibrational coherence in H2+ ions produced by a few-femtosecond long attosecond pulse train (APT) can be controlled by using a pair of APTs and varying their relative time-delay [1-3]. In the latter experiments, we could show that the degree of electronic coherence in H2+ ions produced by a pair of isolated attosecond pulses (IAPs), could similarly be controlled by varying their relative delay [4]. Demonstrating the sensitivity of electronic coherences to quantum entanglement is particularly significant, since electronic coherences underlie the observation of time-dependent electron motion, the raison d’être of attosecond science.

BIOGRAPHY

Prof. Marc Vrakking completed his Phd at the University of California at Berkeley in 1992. After postdoc positions at the National Research Council (Ottawa) and the Vrije Universiteit Amsterdam, he led a scientific group at the FOM Institute for Atomic and Molecular Physics (AMOLF) in Amsterdam from 1997 to 2011. While at AMOLF, he initiated a research program focusing on the use of ultrashort (femtosecond and attosecond) extreme-ultra-violet (XUV) and X-ray laser pulses in studies of time-resolved atomic and molecular dynamics. In March 2010 he was appointed as director at the Max-Born Institute (MBI) in Berlin, and as a professor of physics at the Freie Universität Berlin. At MBI, Marc Vrakking is the head of Division A (“Attosecond Science”), and leads a team of researchers that are both further developing and applying techniques to study electron dynamics on attosecond timescales as well as nuclear dynamics on femtosecond timescales.

Lihong Wang

California Institute of Technology, USA

ABSTRACT

We developed photoacoustic tomography (PAT) for deep-tissue imaging, offering in vivo functional, metabolic, molecular, and histologic imaging from organelles to entire organisms. PAT combines optical and ultrasonic waves, overcoming the optical diffusion limit (~1 mm) with centimeter-scale deep penetration, high ultrasonic resolution, and optical contrast. Applications include early cancer detection and brain imaging.

Additionally, we developed light-speed compressed ultrafast photography (CUP), capable of capturing the fastest phenomena, such as light propagation, in real time. CUP, with a single exposure, captures transient events on femtosecond scales. CUP can be paired with various front optics, from microscopes to telescopes, facilitating diverse applications in fundamental and applied sciences, including biology and cosmophysics.

Further, our research extends to quantum entanglement for imaging. Quantum imaging utilizing Heisenberg scaling enhances spatial resolution linearly with the number of quanta, outperforming the standard quantum scaling’s square-root improvement.

BIOGRAPHY

Lihong Wang is Bren Professor of Medical and Electrical Engineering at Caltech. Published 615 journal articles (h-index = 165, citations = 117K, #1 most cited in optics according to Stanford/Elsevier). Delivered 630 keynote/plenary/invited talks. Published the first functional photoacoustic CT, 3D photoacoustic microscopy, and light-speed compressed ultrafast photography (the world’s fastest camera). Served as Editor-in-Chief of the Journal of Biomedical Optics. Received Goodman Book Award; NIH Outstanding Investigator, NIH Director’s Transformative Research, and NIH Director’s Pioneer Awards; Optica Mees Medal and Feld Award; IEEE Technical Achievement and Biomedical Engineering Awards; SPIE Chance Award; IPPA Senior Prize; honorary doctorate from Lund University, Sweden. Inducted into the National Academy of Engineering.