Category
- Spectroscopy and Spectrometry » Electron Spectroscopy
Booking Details
Broad spot sample cleaning source
Facility Management Team and Location
Prof. Maniraj Mahalingam
Prof. Amartya Mukhopadhyay
Prof. Manoj Neergat
Prof. Saurabh Vijaykumar Lodha
Prof. T Kundu
Prof. Rohit Srivastava
Prof. Debabrata Maiti
Prof. Smrutiranjan Parida
Prof. Dinesh Kabra
Prof. R Murugavel
Prof. Shaibal K. Sarkar
Prof. Sankara Sarma
V. Tatiparti
Prof. Ashutosh Gandhi
Prof. Arindam Sarkar
Facility Features, Working Principle and Specifications
- Automated sample handling and programming of experiments for high thru put analysis
- High energy resolution and high sensitivity (uses both electrostatic lens and magnetic immersion lens)
- Automated charge neutralizer for analysis of insulating samples
- Parallel 2D- XPS imaging and mapping of elements as well as chemical state (Spatial resolution ~ 1 um)
- Depth profiling (Zalar rotation is also available)
- Angle dependent spectroscopy (Compucentric)
- Scanning Auger microscopy
- High transmission electron energy analyzer
- High flux dual anode X-ray, High flux UV source, and monochromatic X-ray source
- AES/SEM/SAM electron gun
- Low energy charge neutralization source
- Broad spot sample cleaning source
Electron spectroscopy for chemical analysis (ESCA) instrument comprises of X-ray photoelectron spectroscopy (XPS), Ultra-violet photoelectron spectroscopy (UPS) and Auger electron spectroscopy (AES) / Scanning Auger Microscopy (SAM).The surface to be analyzed is placed in a vacuum environment and then irradiated with photons (X-ray or Ultra-violet). The incident photons release electrons (called photoelectrons) from their electronic structure (core-levels and valence band) and ionize the atoms. The kinetic energy and the number of photoelectrons are precisely measured and counted respectively using an analyzer-detector based on which the binding energy and the intensity of the photoelectron are determined. AES/SAM is based on the Auger effect (series of internal relaxation events upon ionization of core level) leading to emission of electrons called Auger electrons. It uses primary electron beam (3 to 10 keV) and the possibility to focus and scan this primary electron beam in nm and μm range. The Auger electrons are part of the secondary electron spectrum with characteristic energy allowing one to identify the emitting element. The experimental setup is somewhat similar to that of SEM with a difference, that is, the electrons are not only used for imaging but also for chemical identification of the surface atoms.
Limitations: ESCA can detect all the elements except H and He. The detection limit is 0.1%
Instructions for Registration, Sample Preparation, User Instructions, Precautionary Measures and Charges
- Internal users can register online.
- External users need to down load registration form and submit it to lab along with the requisite demand draft. The samples should be submitted personally on the day of allotted time slot. Analysis will be performed on the next day and results will be sent through email.
- Getting Back the samples: Users desiring to get back the samples need to mark on the form. Collect them from the lab between 9:30 AM to 11:00 AM after two-three days of completion of the work (intimated through mail) and uncollected samples will be disposed off after ten days of intimation of the completion of the work and no reminders will be sent.
- Maximum size of samples should be 10x10x5 mm. Smaller samples of the size 5 mm x 5 mm or 5 mm diameter are more suitable. For samples of different sizes, the user is required to contact the ESCA laboratory staff.
- Label the samples only on the sample containers. Sample labels/codes shall be of three letters/number.
- ESCA analysis is surface sensitive. Do not contaminate the surface of your samples by any means; including touching them with or without gloves to be analysed
- The sample should be completely dry and it should be stable in ultra-high vacuum (no out-gassing allowed).
- Powders should be made into pellets or from a thin coating on a clean conducting substrate like silicon, aluminium or copper foil. Pressing powder in to indium foil is also another method .User should clearly mention if the sample needs etching (surface cleaning) before recording the data. It may be noted that the etching may alter the chemical composition and chemical state to some extent; which needs to be taken into account when interpreting the data.
- Samples containing organic molecules / polymers and some high vapour pressure elements such as Na, K, S, P, Zn, Se, As, I, Te or Hg are not suitable for depth profile analysis.
- UPS and Auger is possible only on sufficiently conducting samples. Insulating samples in the form of very thin films on the conducting substrate may work.
- Registered user will be allotted time as per queue.
- User should submit the samples to the ESCA lab between 9:30 AM and 11:00 AM on the scheduled day.
- Samples will be loaded in to the system on the submitted day and analysis will be carried out after 4 to 6 hours or on the next day. Data will be sent through email.
Applications
- ESCA is a surface analytical tool (up to depth ~1nm) :
- Elemental composition of surface and quantification of there relative concentrations with some limitations
- Chemical states of elements
- Relative quantification of chemical state of each element
- Thickness of thin films
- Depth profiling
- Spatial distribution of material