Documentation for the Atomic Emissions
Fri Jul 25 18:56:07 PDT 1997
The Atomic Emissions applet demonstrates the behavior of an electron
as it changes states in the orbit of an atom, by absorbing energy and
This document gives an overview of use and a history of the creation
of this applet.
All sourcecode to the classes contained in this package, except
those specified below, are Copyright (C) 1997 by the University of
Documentation for the Atomic Emissions package
Table of Contents
1.5 Applet components
1.6 Measured items
2.4 The Virtual Laboratory
Values are computed with the following equations:
- l = hc/e
- e = hc/l
- electron volts
Plank's constant (h)
- 2 * PI * 0.6582E-15
The speed of light (c)
All of the calculations are precise to 16 bits. Some calculations are
done in 32 bits, but are then rounded to 16 bits. Wavelengths are
displayed as integers (the floating point part is truncated, not
rounded). At times, wavelengths are considered equal if they are
equal to two decimal places. PI is a 32 bit floating point number.
There are three distinct applets which can be used in varying
- The main applet. This applet shows
the electron states and an electron, and displays the waves which are
emitted from state changes. This applet can be set up to be either a
passive receptor for light, for use with the LightSource applet, or as
an interactive applet where the user chooses the state changes. The
interactive function of the applet allows the user to choose a state
to which the electron is excited. They then may choose the first
state the electron drops to. After this, the electron drops to states
chosen at random until the electron is at the ground state. The
energy states have energy levels defined in an applet parameter tag,
as are the probabilities that the electron will drop to any given
- The LightSource applet is
attached to an instance of the AtomicEmission applet
(specified by a name attribute in the applet tag of the AtomicEmission
applet). It allows the user to choose from a set of wavelengths
should this be energy levels? and then start the emission
of photons. Photons strike the AtomicEmission atom,
which absorbs the energy, and begins a state change process.
- This applet provides a graph of the
number of photons of each wavelength which have been emitted by a
given instance of the AtomicEmission applet (attached as is the
Two of the applets, SpectralOutput and LightSource, are
useless if not attached to an AtomicEmission applet. SpectralOutput
may be used without LightSource being used, but it makes little sense
to use LightSource without using SpectralOutput.
Behavior of the AtomicEmission applet (which in some cases effects the
behavior of the other applets) can be modified:
- The delay between state changes can be specified by a parameter
applet tag to the AtomicEmission applet. It makes sense to lower this
value for automatic generation of largish amounts of data. This
parameter's name is delay, and values are specified in
milliseconds. This parameter defaults to 1500.
- The interactivity of the AtomicEmission applet is also toggled
by a parameter tag. The parameter's name is
interactive and the value is either true or false.
This parameter defaults to a value of true.
- A third tag specifies the starting state of the electron. This
is for simulation of atoms in high-energy environments, such as suns,
where the collisions of atoms keeps the electrons in a constantly
excited state. This parameter is named start state and
is given an energy level for a value. The default value is the
ground, or lowest, state.
Wavelengths, energy levels, and frequency statistics are reported by
the AtomicEmissions and SpectralOutput applets.
The idea for this applet was presented by Greg Bothun. Dr. Bothun is a
professor of astrophysics at the University of Oregon and one of the
most prolific faculty members of this campus.
Most, if not all, of the non-trivial graphics are provided by Amy
Hulse, a graphic artist under the employ of Dr. Bothun. All other
graphics, IE, the ugly stuff, is Sean's fault. The AtomicEmissions
applet unfortunately does not contain any of Amy's work.
All applets at this site have been programmed by
Sean Russell. Sean is a
full time software developer in the employ of Dr. Bothun. The
AtomicEmissions applet uses two third-party packages:
The Virtual Laboratory is a research project that endeavors to
discover if the quality and availability of education can be improved
by changing the course material to online, interactive multi-media.
- The XML parser is Lark, a really nifty XML parser that I
discovered after completing about 50% of an XML parser of my
own. Funny thing is, the documentation for Lark contains no mention of who the author is or how to contact him, but if you poke around on Textuality's site, you will find out that Textuality is the consulting firm of Tim Bray. Thanks, Tim!
- The graph tool is part of the teaset java package, which is a
simply huge package of pretty useful classes. The home page for the people
who develop the Tea Set is the InetSoft page.
- To improve general access to higher education resources
- To stimulate the desire to learn
- To provide a simulated increase in university resourses
- To increase up-to-date, dynamic information access for
This document was generated from the XML by Lark's xh processor.