The HARPIA comprehensive spectroscopy system performs a variety of sophisticated time-resolved spectroscopic measurements in a compact footprint. It offers an intuitive user experience and easy day-to-day maintenance meeting the needs of today’s scientific applications. Extension modules and customization options tailor the HARPIA system to specific measurement needs.

The system is built around the HARPIA-TA transient absorption spectrometer and can be expanded using time-correlated single-photon counting, Kerr gate and fluorescence upconversion (HARPIA-TF), third beam delivery (HARPIA-TB), and microscopy (HARPIA-MM) modules. HARPIA is designed for easy switching between measurement modes and comes with dedicated data acquisition and analysis software. Each module is contained in a monolithic aluminum body ensuring excellent optical stability and minimal optical path lengths.

For a single-supplier solution, the HARPIA spectroscopy system is combined with a PHAROS or a CARBIDE laser together with ORPHEUS series OPAs. HARPIA also supports Ti:sapphire lasers with TOPAS series OPAs.

APPLICATIONS

Transient absorption and reflection in bulk and microscopy
Multi-pulse transient absorption and reflection
Time resolved fluorescence: Femtosecond fluorescence upconversion, Kerr gate, TCSPC
Femtosecond stimulated Raman scattering (FSRS)
Intensity-dependent transient absorption and reflection
Flash photolysis – nanosecond transient absorption

PROCESSES EXPLORED BY ULTRAFAST SPECTROCOPY

Charge transfer (electron, proton)
Solvation
Vibrational relaxation
Exciton energy transfer
Photoreaction dynamics

Video presentation

Transient Absorption, Pump-Probe (HARPIA-TA)

Configuration	UV-VIS	VIS	VIS-NIR	UV-VIS-NIR	MIR
Measurement range	350 – 1100 nm	460 – 1100 nm	460 – 1600 nm	350 – 1600 nm	2000 – 13000 nm
Pump range	240 – 1100 nm				240 – 700 nm
Delay range (resolution)	8 ns (8.3 fs)				4 ns (4.2 fs)
Temporal resolution	≤ laser pulse duration or better
Laser repetition rate ¹⁾	1 – 200 kHz
Maximum data acquisition rate	4000 spectra/s				Laser repetition rate

Higher repetition rates available; contact sales@lighton.com for details.

Flash Photolysis – Nanosecond Transient Absorption (HARPIA-TA-FP)

Module	HARPIA-TA-FP				HARPIA-TA-FP-UV
HARPIA-TA module	UV-VIS	VIS	VIS-NIR	UV-VIS-NIR	UV-VIS	VIS	VIS-NIR	UV-VIS-NIR
Measurement range	450 – 1100 nm		450 – 1600 nm		350 – 1100 nm		350 – 1600 nm
Delay range	up to 8 ms				up to 500 μs
Delay resolution	100 ps
Temporal resolution	2 ns				1 ns

Kerr gate, Fluorescence Upconversion, and TCSPC (HARPIA-TF)

Module	HARPIA-TF
Mode	Kerr gate	Fluorescence upconversion	TCSPC
Spectral range	250 – 1100 nm	330 – 820 nm	220 – 820 nm ¹⁾
Pump range	240 – 1100 nm
Temporal resolution	400 – 500 fs	≤ laser pulse duration or better	< 180 ps ²⁾
Max measurement range	8 ns		∞ ³⁾
Delay resolution	8.3 fs		n/a
Gate beam requirements	20 – 25 μJ		n/a
Compatible with	TCSPC		Kerr gate or fluorescence upconversion

Spectral range is extendable to NIR; contact sales@lighton.com for details.
High-speed detector available (< 50 ps); contact sales@lighton.com for details.
Maximum measurement range depends on the phosphorescence signal.

FSRS, Multi-pulse time-resolved transient absorption and reflection (HARPIA-TB)

Module	HARPIA-TB
Delay range (resolution)	4 ns (4.2 fs)

Transient absorption and Reflection microscopy (HARPIA-MM)

Module	HARPIA-MM
Spatial resolution ¹⁾	monochromatic	polychromatic
Spatial resolution ¹⁾	< 2 µm	< 10 µm
Full spectral range	460 – 1100 nm
Pump range	240 – 700 nm
Temporal resolution	500 fs
Maximum working distance ²⁾	13 mm
Sample motion range	13 × 13 × 13 mm

White light generation has axial color at focus and wavelength-dependent mode size and NA. Focused white light will exhibit focus shift and spot size variation depending on the chosen spectral range. Polychromatic spot size is given at full spectral range, monochromatic is at 500 nm with a 10 nm bandwidth.
Depends on the objective used.

Dimensions

Model	Physical dimensions (L × W × H) ¹⁾
HARPIA-TA	730 × 420 × 160 mm
HARPIA-TA Sample chamber area (L × W) ²⁾	205 × 215 mm
HARPIA-TF	571 × 275 × 183 mm
HARPIA-TB	670 × 252 × 183 mm

Without external spectrograph.
External sample placement option is available.

Ultrafast Transient Absorption Spectrometer (HARPIA-TA)

The HARPIA-TA ultrafast transient absorption spectrometer provides pump-probe measurement functionality in a HARPIA system. Several probe light configurations and detection options are available: from a photodiode for single‑wavelength detection to white-light supercontinuum probing combined with spectrally-resolved broadband detection. HARPIA-TA features extensive options providing pump beam position tracking and alignment, pump polarization control, supercontinuum generator switching, sample positioning, and switching between transient absorption and transient reflection measurements. Broadband probe options cover from UV to MIR. The probe delay stage is configurable up to 8 ns.

HARPIA-TA is compatible with cryostats, peristaltic pumps, and other accessories. The capabilities of the spectrometer can be further extended using extension modules.

HARPIA-TA ultrafast transient absorption spectrometer

HARPIA optical layout for pump-probe experiments

HARPIA-TA with internal cryostat mounting option

Flash Photolysis – Nanosecond Transient Absorption Module (HARPIA-TA-FP)

The flash photolysis experiment is designed to measure the long-lived states of molecular systems. The principle of flash photolysis is analogous to the femtosecond transient absorption (TA) experiment but with a delay in a nanosecond–millisecond range.

Time-Resolved Fluorescence Module (HARPIA-TF)

Time-resolved fluorescence spectroscopy carries information on the molecular processes in the excited states. HARPIA-TF combines different measurement modes, thus allowing the observation of fluorescence dynamics at different time scales. Using a high-repetition-rate PHAROS or CARBIDE laser, the fluorescence dynamics can be measured while exciting the samples with pulse energies down to several nanojoules.

Modes

Kerr gate.
Easy to use for fs fluorescence measurements. Simpler alignment and maintenance. The entire spectrum is measured at once.
Fluorescence upconversion (FU).
Better temporal resolution for measuring fast fluorescence events.
Time-Correlated single-photon counting (TCSPC).
Fluorescence lifetime measurements are extendible to measure phosphorescence signals.

HARPIA-TF Femtosecond Fluorescence Upconversion and TCSPC Module

HARPIA optical layout for fluorescence upconversion measurements

Principle of time-correlated single-photon counting (TCSPC)

Principle of time-resolved fluorescence upconversion

Principle of Kerr gate spectroscopy

Third Beam Delivery Module (HARPIA-TB)

When standard spectroscopy tools are not enough to unravel the intricate ultrafast dynamics of photoactive systems, multi-pulse time-resolved spectroscopic techniques can be utilized to yield additional insight. It allows an additional temporally-delayed laser pulse (up to 4 ns) to be introduced before or during the pump-probe interaction to perturb the ongoing photodynamics.

Modes

Femtosecond stimulated Raman scattering (FSRS).
Delivering frequency-narrowed ps pulses allows to perform FSRS measurements. It is a relatively recent yet moderately widespread time-resolved spectroscopy technique for observing changes in the vibrational structure of optically excited molecular systems.
Multi-pulse time-resolved transient absorption and reflection.
The pump-pump-probe (PDP), Pump-repump-probe (PrPP) and Pre-pump-pump-probe (pPPP) techniques is a way to manipulate the reactions and access new regions of the higher excited states.

HARPIA-TB Third Beam Delivery Module

HARPIA optical layout for multi-pulse experiments

State transitions and pulse timing in multi-pulse time-resolved transient absorption spectroscopy

Illustration of state transitions and pulse timing in multi-pulse transient absorption spectroscopy

Illustration of Femtosecond stimulated Raman scattering (FSRS)

Microscopy Module (HARPIA-MM)

HARPIA-MM is a microscopy module add-on to the HARPIA-TA spectrometer, which enables spatially resolved pump-probe measurements. It allows the acquisition of time-resolved spectra at a fixed position, difference absorption images at a fixed probe delay, and other types of data.

The microscopy module features a motorized XYZ sample stage, broadband, and monochromatic probe options, as well as transmission and reflection modes, and brightfield mode to observe the sample and to determine the pump-probe spot location.

Modes

Switching between bulk and microscopic pump-probe modes is implemented using self-contained modules, allowing experiment reconfiguration without disturbing the sample.

Microscopy module
Bulk module

Modules for bulk and microscopic pump-probe modes

HARPIA‑TA body with microscopy module installed

HARPIA‑TA with microscopy module installed

HARPIA-TA with bulk module installed

HARPIA-TA with microscopy module installed

Optical scheme for brightfield mode of HARPIA-MM

Optical scheme for transmission mode of HARPIA-MM

Optical scheme for reflection mode of HARPIA-MM

Options

Cryostat Mounting.
HARPIA-TA supports cryostats that can be mounted externally or internally.

Sample Stirrer.
Liquid samples are mixed up to avoid overexposure and ensure fresh sample.

Motorized Pump Mirror.
Used to automatically optimize pump and probe overlap.

External Beam Steering.
To lock the optical beam paths for OPA wavelenghts (350 – 1100 nm).

Beam Profiler.
For checking beam shape/size at any position before/after measurement inside HARPIA

Drawings

Complete Ultrafast Spectroscopy System HARPIA

Drawing of HARPIA system with HARPIA-TB and HARPIA-TF modules

HARPIA-TA ultrafast transient absorption spectrometer

HARPIA-TF Femtosecond Fluorescence Upconversion and TCSPC Module

HARPIA-TB Third Beam Delivery Module

Optical Layouts

HARPIA optical layout for pump-probe experiments

HARPIA optical layout for fluorescence upconversion measurements

HARPIA optical layout for multi-pulse experiments

Optical scheme for brightfield mode of HARPIA-MM

Optical scheme for transmission mode of HARPIA-MM

Optical scheme for reflection mode of HARPIA-MM

Principles of operation

Principle of time-correlated single-photon counting (TCSPC)

Principle of time-resolved fluorescence upconversion

Principle of Kerr gate spectroscopy

Illustration of state transitions and pulse timing in multi-pulse transient absorption spectroscopy

Illustration of Femtosecond stimulated Raman scattering (FSRS)

HARPIA Service App – Control and Data Acquisition Software

A single software solution for all measurement modes, featuring:

User-friendly interface
Measurement presets
Measurement noise suppression
Diagnostics and data export
Continuous support and updates
API for remote experiment control using third-party software (LabVIEW, Python, MATLAB)

CarpetView – Data Analysis Software

An ultrafast spectroscopy data analysis software, featuring:

Advanced data wrangling: slicing, merging, cropping, smoothing, fitting, etc.
Advanced global and target analysis
Probe spectral chirp correction, calibration and deconvolution
Support for 3D data sets (2D electronic spectroscopy, fluorescence lifetime imaging)
Publication-ready figure preparation and data export

Screenshots

HARPIA Service App main window

CarpetView main window

Global analysis windows of CarpetView

Target analysis windows of CarpetView

HARPIA performance at high repetition rate

The HARPIA spectroscopy system achieves an excellent signal‑to‑noise ratio at high repetition rate and low energy excitation conditions. The graphs below compare the signal-to-noise ratio (SNR) of difference absorption spectra obtained with a Ti:Sapphire laser operating at 1 kHz and a PHAROS laser operating at 64 kHz with the same acquisition time.

Measured difference absorption spectra of CdSe/ZnS quantum dots using low- and high-repetition rate lasers with 5 s acquisition time.

Best-effort SNRs, achieved with HARPIA-TA spectrometer driven by a Ti:Sapphire laser at 1 kHz (magenta) and a PHAROS laser at 64 kHz (blue).

Pump probe Measurement (HARPIA-TA)

Pump probe Measurement Data Samples

Spectral dynamics of beta-carotene in solution acquired using HARPIA-TA. Measurement conditions: 100 kHz repetition rate, 490 nm pump wavelength, < 10 nJ pump pulse energy, 13 s per spectrum (per delay point) acquisition time.

Pump-probe dynamics of GaAs wafer in IR measured using signal and reference single-channel detectors. Measurement conditions: 75 kHz repetition rate, 700 nm pump wavelength, 1 s/point acquisition time.

Kerr gate, Fluorescence Upconversion, and TCSPC Measurement (HARPIA-TF)

Kerr Gate Measurement Data Samples

Kerr gate measurements in DCM illustrate the method’s ability to probe fluorescence evolution with a sub-picosecond temporal resolution. Here we see how the fluorescence red-shifts during the early times of the spectral evolution.

Kerr gate measurements in beta-carotene generry showcase the resolution of the measurement. The S2→S0 fluorescence of carotenoids is ultrafast (<100 fs), therefore the measured data is more or less IRF-limited.

Fluorescence Upconversion Measurement Data Samples

Fluorescence dynamics of DCM laser dye in solution acquired using HARPIA-TF in fluorescence upconversion mode. Measurement conditions: 100 kHz repetition rate, 430 nm pump wavelength.

TCSPC Measurement Data Samples

Fluorescence dynamics of DCM laser dye in solution acquired using HARPIA-TF in TCPSC mode. Measurement conditions: 100 kHz repetition rate, 430 nm pump wavelength.

FSRS and Pump-dump-probe Measurement (HARPIA-TB)

Femtosecond stimulated Raman spectroscopy (FSRS) Measurement Data Samples

Femtosecond stimulated Raman scattering dynamics of neoxanthin

FSRS dynamics of neoxanthin using Harpia-TA with Harpia-TB module. Measurement conditions: 25 kHz repetition rate, 440 nm actinic pump wavelength, 200 nJ pulse energy, 530 nm Raman pump wavelength, 300 nJ pulse energy.

Pump-dump-probe Measurement Data Samples

Pump-dump-probe dynamics of DCM laser dye with dump pulse resonant to the emission band of DCM. Measurement conditions: 50 kHz repetition rate, 515 nm pump wavelength, 700 nm dump wavelength, 21 ps dump delay, 90 nJ pump pulse energy, 190 nJ dump pulse energy.

Spatially resolved pump-probe measurement (HARPIA-MM)

Single perovskite crystallite pump-probe spectral kinetics, pump at 400 nm. Pump-probe spot marked by the small circle

Single perovskite crystallite pump-probe kinetics. Pump-probe spot marked by the small circle. Measurement conditions: 400 nm pump wavelength, 200 kHz repetition rate, 2 nJ pump pulse energy, 0.5 s/spectrum acquisition time, and Plan Fluor 4x/0.13 objective.

Publications

Improved Crystallization of High-Solubility Non-Fullerene Electron Acceptors for Enhanced Photoelectric Conversion Efficiency: Effect of the Terminal Group

G. Ran, X. Shan, H. Lu, Y. Liu, Z. Bo, and W. Zhang, The Journal of Physical Chemistry C (2023).

Intramolecular and Intermolecular Interaction Switching in the Aggregates of Perylene Diimide Trimer: Effect of Hydrophobicity

P. Su, G. Ran, H. Wang, J. Yue, Q. Kong, Z. Bo, and W. Zhang, Molecules 7 (28), 3003 (2023).

Transient absorption spectroscopy HARPIA HARPIA-TA

Solution-grown BiI/BiI3 van der Waals heterostructures for sensitive X-ray detection

R. Zhuang, S. Cai, Z. Mei, H. Liang, N. Zhao, H. Mu, W. Yu, Y. Jiang, J. Yuan, S. Lau et al., Nature Communications 1 (14) (2023).

Transient absorption spectroscopy ORPHEUS HARPIA HARPIA-TA

Atomic structure of a seed-sized gold nanoprism

Y. Song, Y. Li, M. Zhou, H. Li, T. Xu, C. Zhou, F. Ke, D. Huo, Y. Wan, J. Jie et al., Nature Communications 1 (13) (2022).

Transient absorption spectroscopy HARPIA HARPIA-TA

Charge Photogeneration and Recombination in Fluorine-Substituted Polymer Solar Cells

R. Hu, Y. Liu, J. Peng, J. Jiang, M. Qing, X. He, M. Huo, and W. Zhang, Frontiers in Chemistry 10 (2022).

Transient absorption spectroscopy ORPHEUS PHAROS HARPIA HARPIA-TA

Cobalt(III) Carbene Complex with an Electronic Excited-State Structure Similar to Cyclometalated Iridium(III) Compounds

N. Sinha, B. Pfund, C. Wegeberg, A. Prescimone, and O. S. Wenger, Journal of the American Chemical Society 22 (144), 9859-9873 (2022).

Transient absorption spectroscopy ORPHEUS PHAROS HARPIA HARPIA-TA

Dopamine Photochemical Behaviour under UV Irradiation

A. Falamaş, A. Petran, A. Hada, and A. Bende, International Journal of Molecular Sciences 10 (23), 5483 (2022).

Fluorescence spectroscopy ORPHEUS PHAROS HARPIA HARPIA-TF

Effects of polyethylene oxide particles on the photo-physical properties and stability of FA-rich perovskite solar cells

R. K. Koech, Y. A. Olanrewaju, R. Ichwani, M. Kigozi, D. O. Oyewole, O. V. Oyelade, D. M. Sanni, S. A. Adeniji, E. Colin‑Ulloa, L. V. Titova et al., Scientific Reports 1 (12) (2022).

Transient absorption spectroscopy ORPHEUS CARBIDE HARPIA HARPIA-TA