Re: paleonet Acid Etching for SEM: Short addendum

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On Wed, 10 Sep 2003, Peg Yacobucci wrote:

> Date: Wed, 10 Sep 2003 15:52:45 -0400
> From: Peg Yacobucci <mmyacob@bgnet.bgsu.edu>
> Reply-To: paleonet@nhm.ac.uk
> To: PaleoNet@nhm.ac.uk
> Subject: paleonet Acid Etching for SEM
>
> Howdy all,
>
> Here's a question I'm forwarding from a student.
>
> I am looking for microfossils (bacteria, algae, etc.) in travertines.  I
> have multiple samples that I want to run under SEM and it has been suggested

Dear Peg,
Dear Justin,

and here a short addendum for better images:

a few months ago there where hints on this list regarding better
depth resolution with light microscopy i.e.: Making a picture
in each level of focus and merging them with software.

The same might, particularly for SEM apply for software that
generates 3D pictures from two different 2D photos (e.g. just rotating
the sample tray a few degrees).

All aspects of contour enhancement by software can be applied in the
postprocessing.

2) You referred to your material, such as algae.

If these are fossilized algae like dasyclad algae there are limits.

If your algae are for example recent diatoms (or subrecent) you
have different types of material in the cells e.g. rests of
lipids, SiO2 and so forth (e.g. your travertine question refers
also to algae that live on them, compared to diatoms making
beach boulders slippery).

These materials scatter electrons back differently
(e.g. different penetration, absorption etc.).

Thus careful adjustment of voltage (e.g. different values, a picture
with each setting, further processing) could also reveal further details.

>
> Thanks,
>
> Justin Richardson
> Dept. of Geology
> Bowling Green State Univ.
>
>
Best regards, Peter

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Dr. Peter P. Smolka
University Muenster
Geological Institute
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