Shaky Nano Property

1
ShakyNano Property 2
All things shake, wiggle, shiver and move all
around at the nanoscale.
2
Brownian Motion
In both cases the fluorescent particles are 2
microns in diameter. The left picture shows
particles moving in pure water the right picture
shows particles moving in a concentrated solution
of DNA, a viscoelastic solution in other words.
The movies are 4 seconds of data, total you can
see a slight jump in the movie when it loops
around. http//www.deas.harvard.edu/projects/weitz
lab/research/brownian.html
3
Model of Brownian Motion
http//www.ap.stmarys.ca/demos/content/thermodynam
ics/brownian_motion/brownian_motion.html
4
Basic Thermodynamics
Zeroth Law If two systems are in thermal
equilibrium with a third system, they are in
thermal equilibrium with each other. First Law
Energy in the universe is conserved (it is also
conserved in a closed system). Second Law
Entropy increases
5
TEMPERATURE
What is Temperature anyway? What is it a measure
of ?
MOTION
In specific Scientific Terms Temperature is a
measure of the average kinetic energy of the
particles in a system.
6
What is Energy?
Capacity to do Work. What does this mean?
Energy
EM Radiation Light X-rays microwaves
Stored (Potential) Chemical Nuclear Magnetic Ele
ctrostatic Mass
Motion (Kinetic)
7
Energetics of an Explosion
TNT
In what form is the energy?
8
Energetics of an Explosion
Bang!
In what form is the energy?
9
Heat is nano-scopic motion
Very, Very cold
Warm
Hot
10
Flow of Heat
11
Brownian Motion in a Fluid
12
Thermal Energy
Ethermal1/2 k Temperature k Botzmanns
constant (1.3810-23J/K) Ethermal1/2 kT
Average Energy of each degree of freedom in a
system.
At room Temperature, Ethermal 410-21 J or
0.025 eV
13
Fahrenheit, Celsius, Kelvin
Kelvin
273
373
173
73
0
473
573
100
Celsius
300
0
-200
-100
200
-273
Fahrenheit
572
32
212
-328
-148
-459
392
14
Kinetic Energy
Ekinetic1/2 (mass)(velocity)2 Ekinetic 1/2 mv2
We can set the thermal energy of an object equal
to its kinetic energy to see how fast it is
moving. This is appropriate for relatively free
particles.
EkineticEthermal 1/2 mv2 1/2 kT v(kT/m)1/2
15
Thermally induced Kinetic Energy
v(kT/m)1/2 (appropriate for a free particle)
Person 100kg 610-12m/s Grain of Sand 10
mg 710-8m/s (10nm/s) 10 micron bead 410-12kg
20 microns/s 1 micron bead 410-15kg 700
micron/s Virus 510-19kg 9 cm/s Oxygen
Molec. 510-26kg 270 m/s
16
Equipartition of Energy
17
Phase Transition
18
Simulation of Gas in a Closed Chamber Pressure
19
Thermal VibrationsCarbon Nanotube
20
Challenge Problem for the Brave
How much are atoms shaking at room
temperature? Lets take the case of a water
molecule.
Spring constant between Oxygen and Hydrogen
500 N/m. k 500 N/m
O
H
H
Espring ½ k x2
?
Each degree of freedom has ½ kBT energy (on
average)
Give answer as of bond length