Research Interests

UHV setup to mimic astrophysical reactions

Image: Cornelia Jäger

We developed an ultra-high vacuum (UHV) chamber equipped with a closed-cycle cryostat, which can cool down ice or ice/dust mixtures to temperatures of less than 10 K. Energetic photons or reactive atoms can trigger reactions between molecular components in the ice or between the ice and the dust surface. Chemical reactions are monitored by in situ IR spectroscopy and temperature-programmed desorption in combination with mass spectrometry.

• Closed-cycle He cryocooler (ARS DE-204SB)
• Gas inlet system for the deposition of molecular ices
• Quadrupole mass spectrometer (Hositrad)
• Sources for VUV photons (hydrogen-discharge and a deuterium lamp)
• FTIR spectrometer (Bruker, Vertex 80v) equipped with an external MCT detectetor

Gas-phase condensation setup to mimic the condensation of cosmic dust at high temperatures.

Image: Cornelia Jäger

The gas-phase condensation setup is used to condense dust particles of different compositions such as silicates, oxides, carbonaceous grains, carbides and so on that can be used as analogues of cosmic dust. Laser evaporation of a solid target is performed in the presence of various quenching gases. The condensed grains are adiabatically extracted through a nozzle and a skimmer and deposited on a substrate in the fourth chamber, which can be heated or cooled down up to 6 K. A co-deposition with interstellar molecules on the cold substrate allows us to produce dust/ice mixtures at different temperatures. In situ  FTIR and UV/vis spectroscopy provide spectral data in a very broad wavelength range. In addition, the dust can be processed by exposure to VUV photons or by heating.

• Nd:YAG laser (532 nm; Continuum Surelite)
• Closed-cycle He cryostat
• FTIR spectrometer (Bruker, Vertex 80v) and an external DLaTGS detector and a broadband detector

Photo of the He cluster setup used to study surface reactions between molecular components and reaction energies.

Image: Cornelia Jäger

• Differentially pumped 5-stage He cluster/ droplet beam apparatus
• Liquid helium-cooled supersonic jet source
• Quadrupole mass spectrometer
• Nd:YAG laser (1064 nm, 532 nm, 355 nm; Continuum NY81-20) + dye laser (Lambda Physik Scanmate 1) for the evaporation of dopant atoms or molecules
• Atomic carbon source (homemade)
• Atomic hydrogen source (HABS; MBE-Komponenten)

UHV setup constructed for the deposition of diamonds at high- and low-temperatures.

Image: Cornelia Jäger

UHV setup designed for the deposition of diamonds at high- and low-temperature. The vacuum chamber is topped with a cryocooler (photo right side). Left: The back side of the substrate holder containing a glassy carbon that can be heated or cooled in front of the two active C and H atom sources. A glassy carbon substrate with a circular deposit of carbon. The left corner was treated with diamond polish. The device allows us to study the condensation of C atoms on surfaces from cryogenic temperatures (about 10 K) to high temperatures (1400 K). The effect of VUV irradiation on the processes can also be studied.

• Quadrupole mass spectrometer
• Closed-cycle He cryocooler (APD Cryogenics DE-204SLA)
• Atomic carbon source (homemade)
• Atomic hydrogen source (HABS; MBE-Komponenten)

This setup allows us to measure the UV/vis and IR spectrum of molecules isolated in Ne or Ar matrices. Species in the solid state are brought into the gas phase by thermal evaporation in an oven or by laser vaporization. Isolated species can be ionised by using a H₂ discharge lamp.

• Closed-cycle He cryocooler ARS DE-204SL for sample cooling (6.5 K)
• UV-VIS-NIR with optical fibers (Jasco V-670 EX) and FTIR spectrometer
• Nd:YAG laser (1064 nm, 532 nm, 355 nm, 266 nm; Continuum Minilite II) for laser vaporization
• Thermal evaporation source

Sketch of the CRDS jet experiment.

Image: Gaël Rouillé

• Vacuum chamber housing a heated pulsed valve or a laser-ablation source
• Nd:YAG laser (1064 nm, 532 nm, 355 nm; Continuum Surelite II-20) + dye laser (Continuum ND6000) + SHG stage (Continuum UVT-1) for spectroscopy
• Photomultiplier (Hamamatsu H6780-04) as CRDS optical detector
• Photomultiplier (THORN EMI 9813QB) as LIF detector
• Monochromator (Jobin Yvon HR-320) and CCD camera (Andor iDus DV420A-BU2) as dispersed emission detector
• Digital oscilloscope (Tektronix TDS3052)
• Nd:YAG lasers (1064 nm, 532 nm, 355 nm, 266 nm; Continuum Minilite I) for laser vaporization

Laser pysorolysis setup for the gas-phase condensation of carbonaceous grains and molecules.

Image: Cornelia Jäger

A flow reactor designed for the gas-phase condensation of carbonaceous molecules such as polycyclic aromatic hydrocarbons (PAHs) and carbonaceous grains. Different temperature regimes in the condensation zone could be realised either by a cw CO₂ laser (λ=10.6 µm; power: 100 W)  or a pulsed CO₂ laser  to achieve tempetarures of ≤ 1700 or ≥ 3500 K, respectively.

Analytical characterisation and fractionation of PAHs were performed by high-performance liquide chromatograph (Jasco) equipped with a diode array detector (MD-2010). The device allowed us to fractionate individual components or mixtures of PAHs.

Multimode AFM (Veeco) with controller (Digital Instruments Nanoscope III)

Stereo microscope (Carl Zeiss Stemi 2000-C) with CCD camera (Spindler & Hoyer 230 C) and monitor

At the Institute of Solid-State Physics, the group has access to different ion implanters and Rutherford Backscattering Spectroscopy. The group has also admission to high-resolution transmission electron microscopes (HRTEM) equipped with EDX and Electron Energy Loss spectroscopy at the Otto Schott Institute of Material Science.