Nanoscopy Lab

The interaction of materials with intense electromagnetic radiation modifies the topography and physico-chemical properties of their surfaces [1]. The top layers are ejected from a surface in the extreme case called ablation. Ablation efficiency can be evaluated from the global properties of ablation craters (diameter, depth, shape) dependent on the properties of the incident radiation. A detailed look at the damaged surfaces shows the redistribution and phase transformation of the radiation-affected material. These observations, supported by the results of in situ diagnostics, give insight in to the mechanisms of the interaction between matter and radiation, in our case XUV and/or X-ray, i.e. short-wavelength radiation.

Laser- induced periodic surface structures (LIPSS) [2,3] are interesting phenomena following laser ablation. According to the nature of their origin LIPSS of two kinds can be distinguished. Most of the observed LIPSS-I have a spatial period and orientation strongly dependent on the laser properties (wavelength, polarization, coherence, angle of incidence). They are created due to the interference of the incident laser beam with a field scattered along a surface. Structures of the second kind (LIPSS-II) have spatial periods that are significantly greater than the laser wavelength and depend more on laser intensity than wavelength, when a short-wavelength laser is used for surface irradiation.

[1] D. Bauerle: Laser Processing and Chemistry, 2nd Ed., Springer-Verlag, Berlin, 1996.

[2] A. E. Siegman and P. M. Fauchet: IEEE J. Quantum Electron. QE–22, 1384–1403 (1986).

[3] J. E. Sipe, J. F. Young, J. S. Preston and H. M. van Driel: Phys. Rev. B 27, 1141–1154 (1983).
 

The Nanoscopy Lab was established at the Institute of Physics in 2004 as a joint laboratory of the Department of Laser Plasmas and the Department of Thin Films. The laboratory is equipped with a Dimension 3100 Scanning Probe Microscope (Veeco) controlled by a NanoScope IV Control Station (Veeco). This layout represents a unique tool for analysis of irradiated surfaces due to the fast and easy application of atomic force microscopy (AFM) and scanning tunneling microscopy (STM) techniques. Dimension 3100 SPM

The following characteristics, among others, deserve to be highlighted:

• large samples (up to 200 mm diameter and 12 mm thick) can be investigated
• optical microscopy allows accurate specification of cantilever initial position (see the picture above)
• topography of large areas can be explored by AFM in tapping mode, e.g. 60 micron × 60 micron scan can be measured with a tip velocity 10 microns/s
• detailed images with a resolution of ~ 10 nm can be obtained in various not only topographical modes, e.g. image of electrical or magnetic properties
• SPM is operated in the air but isolated from vibrational and electrical noise from surroundings

A Nomarski BX51 microscope equipped with a digital camera C5060 (both from Olympus) is available in the Nanoscopy Laboratory.