August 29, 2007: Snowflake under electron microscope - Page 2

binky · 08-30-2007, 04:04 PM

Thank you for the snowflake- it is about 105 degrees here in the California desert, so even the thought of snow is comforting

middy · 08-30-2007, 04:08 PM

How do all six arms of the snowflake know to grow into the same shape? That's what I want to know.

glatt · 08-30-2007, 04:10 PM

Quote:

Originally Posted by middy

How do all six arms of the snowflake know to grow into the same shape? That's what I want to know.

I'm pretty sure it's in the genes.

Happy Monkey · 08-30-2007, 04:26 PM

The shape of the center determines the shape of the arms.

xoxoxoBruce · 08-30-2007, 05:47 PM

Starfish syndrome.

Beest · 08-30-2007, 09:59 PM

I usually try and do this at least once each winter, personally I'm going for catching a falling flake, and imaging it without any prep. All that freezing with liquid nitrogen and bombarding with ions might change the structure.
Then again I haven't been successful yet.

Quote:

Originally Posted by Scriveyn

I had been wondering how they did it, beacause electron microscopes can only image objects whose surface is electrically conductive. -

Modern (for at least the last ten years) electron microscopes can image non conducting objects by using a low gas pressure in the chamber, incoming beam ionizes the gas around the beam providing a conducting path to dispel charge.

Low beam currents, and accelerating voltages, also help reduce sample charging in the Field emission type SEMs.

I bet you're sorry you asked now

monster · 08-30-2007, 10:36 PM

Quote:

Originally Posted by Beest

I usually try and do this at least once each winter, personally I'm going for catching a falling flake, and imaging it without any prep. All that freezing with liquid nitrogen and bombarding with ions might change the structure.
Then again I haven't been successful yet.

But you have done some nice pics of a chrysalis. And stuff.

Scriveyn · 08-31-2007, 03:29 AM

Quote:

Originally Posted by Beest

... Modern (for at least the last ten years) electron microscopes can image non conducting objects by using a low gas pressure in the chamber, incoming beam ionizes the gas around the beam providing a conducting path to dispel charge.

Low beam currents, and accelerating voltages, also help reduce sample charging in the Field emission type SEMs.

I bet you're sorry you asked now

Not at all - thanks B.

paxton · 09-08-2007, 10:15 PM

Quote:

Originally Posted by middy

How do all six arms of the snowflake know to grow into the same shape? That's what I want to know.

http://en.wikipedia.org/wiki/Crystallization

08-30-2007, 04:04 PM	#16
binky all hollowed out Join Date: Jan 2005 Location: Ridgecrest, CA Posts: 982	Great timing Thank you for the snowflake- it is about 105 degrees here in the California desert, so even the thought of snow is comforting

08-30-2007, 04:26 PM	#19
Happy Monkey I think this line's mostly filler. Join Date: Jan 2003 Location: DC Posts: 13,575	The shape of the center determines the shape of the arms. __________________ _________________ \|...............\| We live in the nick of times. \| Len 17, Wid 3 \| \|_______________\| [pics]

08-30-2007, 05:47 PM	#20
xoxoxoBruce The future is unwritten Join Date: Oct 2002 Posts: 71,105	Starfish syndrome. __________________ The descent of man ~ Nixon, Friedman, Reagan, Trump.

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08-30-2007, 04:08 PM	#17
middy A Certain Someone Join Date: Aug 2007 Location: Texas Posts: 5	How do all six arms of the snowflake know to grow into the same shape? That's what I want to know.

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