Helios femtosecond transient absorption spectrometer

HELIOS is an automated femtosecond transient absorption spectrometer designed for various femtosecond amplification lasers, including high-energy Ti: Sapphire femtosecond amplifiers and high repetition rate Yb femtosecond amplifiers. Combined with the obtained optical delay block, HELIOS provides good performance and user friendliness.

Product Features

Wide detection spectral range

*Detecting around the basic wavelengths (Ti: Sapphire~800 nm, Yb~1030 nm) requires manual adjustment of the filter.

Spectral resolution optimized for transient absorption
For transient absorption, higher spectral resolution is not always better. It is important to draw all spectral features, but it is also important to provide sufficient detection light for each pixel of the detector. These two parameters resist each other - when the probe light is insufficient, the data may have noise; If there is not enough spectral resolution, some important features may be overlooked. Therefore, we configured the spectral resolution to be sufficient to solve practical problems in condensed phase experiments, but not too high, to allow sufficient detection light on the detector.

8 ns time window, expandable to ms

The ns window is achieved by directly driving high-speed optical delay lines. The delay block optical component adopts a custom designed bracket to improve the repeatability and overall reliability of beam alignment. This delay line has the characteristics of high resolution and high speed. High speed scanning is crucial as it allows for pseudo-random stepping without significantly increasing experimental time. This type of step is very useful for minimizing the effects of laser instability and sample degradation.

The standard 8 ns time window can be extended to ms through the EOS plugin.

Specification of optical delay line:

• Time window: 8 ns

• Resolution: 14 fs

• Minimum step size: 2.8 fs

• Maximum speed:>10 ns/s

• Acceleration:>260 ns/s ^ 2

• Automatic alignment time: 3-5 minutes

• Beam pointing drift:<10 μ m, delay range of 8 ns

Reflection detectionLight management

We use off-axis parabolic mirrors to collimate and focus the detection light in Helios. This resulted in a detection waist of~50 μ m at the sample site. The tightly focused detection beam allows for low-energy excitation using pulses as low as tens of nJ/without sacrificing signal amplitude.
In addition, using reflective optical elements in the detection path can improve the temporal resolution of the device.

Built in automation

• Automatic Optical Delay Line Alignment (Smart Delay LineTM).

• Automatically switch between UV, VIS, NIR, and SWIR spectral ranges.

• Automatic pump beam alignment

detector
All Helios detectors are fiber coupled spectrometers with linear array detectors. Each spectrometer has a concave grating with aberration correction to achieve maximum luminous flux (crucial for high-quality data). The ADC resolution is as high as 16 bits. All detectors are installed in a 19 inch electronic rack outside the optical workbench.

UV-VISUV Visible Range：For this spectral range, we have two detector options:

• CMOSThis 1024 pixel CMOS sensor is highly suitable for high-speed data acquisition. Allow for single laser pulse detection up to 5 kHz. Spectral response: 200-1000 nm. The typical spectral range spans 600 nm (i.e. 350-950 nm).

• CCDSensor: This 2048 pixel backlit CCD sensor is perfect for 1-2 kHz lasers, with very high sensitivity and dynamic range. Spectral response: 200-1000 nm. The typical spectral range spans 600 nm (i.e. 350-950 nm). Spectral acquisition rate - up to 2000 spectra per second.

NIR spectral range:This 256 pixel InGaAs sensor achieves a good balance between spectral resolution and sensitivity. Spectral response: 800-1600 nm. The typical spectral range spans 800 nm (i.e. 800-1600 nm). Spectral acquisition rate - up to 5000 spectra per second.
SWIR spectral range256 pixel InGaAs sensor (spectral response: 1000-2600 nm). The typical spectral range spans 800 nm (i.e. 1600-2400 nm). Spectral acquisition rate - up to 5000 spectra per second.

bigareaSample processing
The spacious (350 mm x 250 mm) sample chamber and detachable side panels facilitate the installation of low-temperature thermostats, translation of sample racks, and even coupling to external magnets. In addition, simply leaving more space around the sample makes it easier to handle it.

Sample rack options
Magnetic stirrers allow the use of enclosed colorimetric dishes (≥ 2 mm long) and can be used with simple colorimetric dish holders. Translating the sample holder can be used to grid thinner colorimetric dishes (not easy to stir), films, wafers, etc. Translating the sample holder can handle both transmitted and reflected samples.

Detecting reference options
HELIOS has an option for the second probe (reference) channel. In this case, the probe beam is split into two before passing through the sample. When one arm passes through the sample, the other arm is directly sent to the reference spectrometer, which monitors fluctuations in the intensity of the probe beam. The main advantage of this method is that it allows users to achieve with fewer average laser pulsesstipulatedSignal to noise ratio. This method is recommended for experiments on low repetition rate and/or easily photodegradable samples with severely limited laser emission times.

Computer controlled filter wheel
Automatic switching, used for different pump energies, etc.

HELIOS Microscope Options
We offer two options to perform spatially resolved transient absorption measurements.

Helios microscope confocal microscopyConfocal microscope	WIDEFILD Microscope
This is actually Helios, which has a very tight beam focusing on the sample. With it, you can extract transient spectra and dynamics from specific points on the sample.	It aims to simultaneously image the dynamic data of multiple points on the sample.

software

HELIOS data acquisition software has built-in support for automatic alignment of all key optical components, which basically does not require manual operation.
The software is also very user-friendly and versatile:

• Automatically align the optical delay block.

• Automatic alignment of pump beam.

• Computer controlled switching between UV, VIS, NIR, and SWIR modes.

• Support computer-controlled translational sample holder.

• Support pump beam louvers.

• Support electric filter turntable for automatic pump strength control.

• Save each individual dynamic scan, so that if the experiment is interrupted (due to laser fluctuations, power outages, etc.), all previous scans will not be lost.

• Threshold adjustment automatic continuous spectrum peak suppression - advanced setting, if the continuous spectrum is unstable, collect data points again.

• When using appropriate optical components, anisotropy calculations are automatically performed and a reference channel is included.

• Support multiple shredders to facilitate custom experiments.

• Provide HELIOS API (Application Programming Interface) for further experimental customization and integration with external applications.

application

Helios IR can be used to monitor the absorption of light induced substances in the mid infrared spectral region. For example, vibrational excited states, charge carriers, and electronic excited states in low bandgap nanomaterials.

Some useful research areas for HELIOS IR are:

• Photophysics

• Materials Science

• photochemistry

• nanoscience

• Photobiology

• Transient spectroscopy method

• Cell Biology

HELIOS owners are using this instrument in various projects:

Light treatment on single-walled carbon nanotubes
Light treatment in fullerene and phthalocyanine trimer
The photophysical properties of two-photon chromophores
Ionic damping in colloidal metal nanoparticles
Nonlinear absorption platinum complex
Surface Plasmon Resonance of Metal Nanoparticles
Silver nanodot fluorescence scintillation
Collecting infrared photons using dye clusters
Acoustic vibrations in gold nanoparticles
Femtosecond Spectroscopy of Lobster Pigments
Material properties of metal nanoparticles
Geometric Isomers of Carotenoids
Photochemistry of cadmium selenide quantum dots
Quantum constraints in photoexcited gold clusters
Nonlinear absorption of PbS nanoparticles
Optical excitation in supramolecular metal rings
Nonlinear absorption and optical confinement in near-infrared
Ultrafast Polarion and Triplet Exciton Formation in Polythiophene Thin Films
Methane Fullerene Cations on Polymer Solar Cells
Electronic Properties of Oligoalkenes and Oligothiophenes
Supramolecular conglomerate of phthalocyanine and porphyrin
Photo induced electron transfer in ruthenium (II)/tin (IV) porphyrin arrays
Light Induced Processes in Metal Supramolecular Boxes
Light Induced Energy Transfer in Rod like Dual Core Ru (II) Complex
Multilayer Tripyridine functionalized Perylene Bisimide Metal Complex
Light Induced Process in Porphyrin Perylene Diimide Symmetric Triad