1. Describe the purpose and general use of an SEM in a brief paragraph. Include possible applications.

2. Draw and explain a schematic, "black box" diagram, of the basic components of a SEM.

3. Discuss production of the electron beam. Describe the physical factors controlling emission, work function of sources and source temperature for W, LaB6 and field emission (Shottkey & cold cathode).

4. Discuss how source electrons are directed toward the sample and focused to a final spot. Discuss "spot" size, instrumental resolution, "working distance", demagnification, divergence angle, the purpose of the apertures, and amount of current reaching the sample. Include a description of electromagnetic lenses, the purpose or function of each lens, and lens aberrations

5. Describe how a scan is accomplished. Describe the production of a scan pattern on the sample and of corresponding image projection on the CRT. Explain how magnification is accomplished. Include a description of raster rotation and dual magnification (to be expanded in relevant labs).

6. Discuss interactions between primary electrons and atoms of the sample. Provide details regarding types of signals generated, sampling depth and signal-dependent resolution.

7. Discuss detection methods for the various signals.

8. Define and describe spatial and spectral resolution for X-rays and other signals.

LAB 1. BASIC OPERATION OF THE AMRAY 1400[AMRAY 1400 (CCR 109)]

Background: Indicate the general purpose and provide a brief description for each of the AMRAY 1400 controls .Discuss the purpose of the check-out procedure (attach handouts).

Describe the procedure for obtaining a photomicrograph with AMRAY 1400 (both polaroid and digital images)

Experimental: Review the highlights of the following procedures: check-out (You must show competence with check-out to proceed)start-upsetting working distance (Objective Lens Coarse/Medium)image focusing ( Z adjustment and Objective Fine)shut-down

Discuss the following items: dark level contrast and brightness sample translation/tilt/rotate (& relation to CRT)image translation & partial field(reduced area) translation (sample/ CRT relation)

Conduct/Discuss the photomicrograph procedure, including: proper dark level, brightness and contrast settings camera brightness and contrast settings effect of various record settings preparation of positives and negatives

 LAB 2. - ASTIGMATISM ADJUSTMENT AND APERTURE CENTERING

(Variable Aperture Centering is a demonstration only) [AMRAY 1400Ô - CCR 109] Background:

Describe the origin(s)of astigmatism and stigmator principles. Explain effects of astigmatism on images. What happens as one goes through objective focus?

Describe the effects of an uncentered variable aperture. What happens as one goes through objective focus?

Experimental:

Discuss the procedure for improving the image using the stigmator.

Describe how the stigmator (x and y , phase and amplitude) compensate for the astigmatism.

How does "AutostigÔ " work?

Describe the procedure for centering a variable aperture.

Lab 3. SAMPLE PREPARATION & EFFECT OF COATING TIME[AMRAY 1400 (CCR 109)]

Background: Provide explanations for: the necessity of a conductive path to the sample the requirements for a clean, dry, degreased sample.

Discuss the various coating methods, including: different coating materials and techniques the proper coatings for secondary electron work vs. X-ray analysis anticipated effects of varying the coating thickness the types of samples that require coatings, and approach to avoiding a coating (low voltage microscopy, environmental SEM’s)

Experimental: Describe the operation of the vacuum system, including the valving sequence for sample exchange. Discuss the general methods of sample preparation prior to the coating operation. Describe the procedure for the gold sputter coater and the carbon evaporator (attach handouts).Discuss and compare photomicrographs and real-time appearance of: different coating thickness on a non-conductive sample (ceramic)ceramic, polymer, biological and metal samples (include prior/post labs)carbon vs. gold vs. no coating for non-conductive samples ( " )various settings for the contrast, dark level, and ability to focus ability a grounded vs. ungrounded metal sample.

[AMRAY 1400Ô - CCR 109]

Background:

Experimental:

Discuss and compare photomicrographs of:

LAB 4b. STEREO PAIRS (including split images) & DUAL MAGNIFICATION

[AMRAY 1400Ô - CCR 128]

Background:

Describe the concept of stereoscopic vision. Describe methods of obtaining stereo information - in particular using a stereo viewer.

Discuss the type of additional information the microscopist can gain through the use of stereo pairs as compared to a single image.

Discuss principles of dual magnification.

Discuss the results obtained from observing to photomicrographs taken at 5 to 10 degrees tilt difference individually and through the stereo viewer.

Use split image recording and dual magnification function.

[AMRAY 1400Ô - CCR 109]

Describe the calibration procedure for a SEM and for digital images.

Discuss the accuracy of the micron marker as shown on photomicrographs, with magnification, changes in operating conditions, microscope maintenance.

Describe the concept of resolution (including figures as necessary) and the various types.

Describe how high/instrumental resolution images are obtained and sample/signal requirements. Explain how the resolution is "improved" with an "ideal" sample.

Experimental:

Calculate the actual magnification, micron marker length and correction factor.

Discuss and compare calibrated photomicrographs taken at varied magnifications using similar methods and calculations.

AmRay 1400Ô - CCR 109

During this lab, which will be scheduled independently with the instructor, you will be expected to show competence in all operations of the Amray 1400. After completing check-out, you are approved for unsupervised operation of the microscope.

Background:

Review Check-out procedure

Experimental:

Review "new " features of AMRAY 1400Ô e.g Procedures and capabilities of the Robinson Detector. Complete check out on an individual basis

LAB 7 - INTRODUCTION TO FIELD EMISSION (FESEM) & DIGITAL MICROSCOPY

[ LEO 982 GEMINIÔ - CCR 107]

Background:

Discuss the optics and features of the FESEM, particularly as distinguished from a conventional microscope

Indicate the general purpose and provide a brief description for each of the LEO Gemini 982Ô controls.

Discuss the purpose of the check-out procedure (attach handouts).

Review procedures (different) from W and LaB₆ SEM’s

Review the highlights of the following procedures:

Discuss the following items printing, storing and processing of digital images astigmatism adjustment and aperture centering with a wobbler review of controls capabilities of system (resolution, zero point of charge, detectors, digital)low voltage microscopy features: 1 nm @ 30 kV, 2.5 nm @ 1 kV; High Intensity (Shottky Source); All Digital (MO & Disk Image Storage); Secondary e^- - In-Lens & ET Detectors; Open Stage-80mm X,Y,Z Joystick/Memory; -15⁰ to 85⁰ Tilt; IR Chamberscope; Hi-Res. Laserjet/Dye Sublimation Prints, EBSP (Diffraction)

LAB 8. ACCELERATING VOLTAGE & IMAGES

[ LEO 982 GEMINIÔ - CCR 107]

Background:

Describe the purpose(s) of varying the accelerating voltage.

Discuss the effect of various accelerating voltages on the primary sample/beam interactions.

Discuss changes in signal-to-noise ratio as a function of accelerating voltage and source type(Conventional W/LaB₆ SEM and FESEM).

Experimental:

Describe the steps used for changing the voltage.

Discuss and compare photomicrographs taken at 20KV, 15KV, 5KV, and/or 2KV (etc) with regard to the effects on:

Compare and discuss photomicrographs of backscattered and secondary electron images for two different samples or two different tilt angles.

 Lab 9. SECONDARY & BACKSCATTERED ELECTRON IMAGES

[ LEO 982 GEMINIÔ - CCR 107]

Background:

Discuss the origin of backscattered electrons. Compare the yield of backscattered and compare/relate to secondary electrons

produced as a function of:

Explain the detection method for backscattered electrons vs. secondary electrons employed by the FESEM using Thornely-Everhardt (TE)detector.

Explain the detection method for backscattered electrons using the "tetra" (quad) detector and other backscatter detectors (Robinson detector).

Explain the detection method for secondary electrons using the in-lens detector. How does the signal differ from a TE detector and graphite lined systems.

Describe the different types of information obtained about the sample using backscattered vs. secondary electrons.

Discuss spatial distribution and sampling depth for backscattered and secondary electrons and specific detectors.

Experimental:

Compare photomicrographs taken with the Everhart-Thornley detector (secondary and backscattered images), in-lens detector and the "Tetra" ("Quad") detectors.

Compare photomicrographs taken with the Tetra detectors using settings A, B, A+B and A-B.

[ LEO 982 GEMINIÔ - CCR 107]

Initial orientation into X-ray spectroscopy and X-ray microanalysis

Background:

Indicate the general purpose and provide a brief description for each of the PGT controls and displays.

Describe the origin of X-rays (Characteristic and Continuous)

Discuss and compare two detection methods (EDS vs. WDS) for X-rays

Describe the effect of analog vs. digital, geometry, intensity, detector size, etc.on X-ray collection and processing

LAB 11. X-RAY SPECTROSCOPY AND MICROANALYSIS -

Background:

Describe how a multi-channel analyzer sorts the collection data.

Describe how position tagged spectroscopy (PTS) sorts the collection data.

Describe the procedure for operation of PGT IMIX & PTS Systems (attach handouts)

Describe how elemental maps, line scans, areas, points are obtained

Experimental:

Discuss the calibration procedure and purpose for using a standard.

Identify the peaks for data collected for an unknown sample.

Discuss the resultant photomicrographs or charts and the procedures for analog and digital:

This lab will be conducted on an individual basis by following the PGT-IMIX handouts. Excerpts from the tutorial provided with the software will guide you through specific exercises. Please maintain all output and printouts for your notebook.

Handouts are provided at the Busch Student Center at Reprographics.