the computer bulletin board Douglas Jones; a t Georgia Tech, Mary Trauner; a t NCSA (Illinois),Tony Baylis; Mike Krogh; Nora Sabelli. Portions of the soilware used were developed a t the National Center for SupercomputingApplications at the University of Illinois a t Urban-Champaign. The author gratefully acknowledges a grant of computer time under educational project # TRA900207N.
Updating an Old NMR Spectrometer Using an ISM PC Computer through the RS-2324 Communication Standard G. Movna and L. Mussio -~~~~-~ ~
~ainte6anceLaboratory Facultad de Quimica Avda. General Flores 2124 Montevideo, Uruguay Users of old FT N M R spectrometers (i.e., Varian XL-100, Bruker HX-90, ek.) have a very limited range of experiments to perform with their machines. Only simple Alternate Pulse sequences are possible. Data manipulation is very difficult and sometimes impossible. This situation is not rare for investigators in developing countries, where the possibility of getting new equipment is low and sometimes machines were purchased during less stringent financial condition. Hardware and Software Modifications Generally computers from the late 60's were connected to their TeleTypes via Current Loops working with relays a t 110 Bauds. The M M 620L TeleType Controller used in the Varian XL-100 FT spectrometer is such a case (10-12). The MC1488 and MC1489, two popular level converter ICs, were used in the modification, replacing the send and receive relays. The baud rate was modified by changing two pairs of capacitors from the send and receive clock signal generators in the TTY Controller board. To get the spectral data a t the PC an RS-232-C handler was necessary. A TTY emulator program has been customized in Turbo Pascal to satisfy our needs. Data is processed in a Turbo Pascal subroutine that is able to edit the spectra and calculagives us the possibility of making on-screen JHH tions and integrations, differencespectroscopy, and to save spectroscopic data by creating a spectra data bank. In order to make it possible for the M M 620L to dump the spectra through the modified TTY Controller, a little M M 620L machine language program that dumps the FID or NMR data table when called from the PC was made. All the original VDM 620L TTY program tapes were backed ' up in MS-DOS format. Conclusion Simple electronic modifications of the W M 620L TTY Controller and connection to a PC, transformed an outdated computer into a relative good data acquisition system. Spectral data now can be handled easily, because it can be taken in disks to the chemists laboratory, making printing and customizing fit to the users need. All the changes discussed here for the Varian W M 620L computer can be adapted simply to make similar improvements on other old NMR computer systems. The most important point to consider is that an old machine A78
Journal of Chemical Education
can be improved with a small amount of money The pmject had an overall cost of $1500 US, including the PC. This is important in developing countries such as Uruguay, where we have lots of time. but not so much monev. A lise ing of the original Turbo pascal program as well & prices and circuit dagrams can be obtained for the authors. Acknowledgment The authors wish to thank Jean F. M. 0 t h and Ignacio Stolkin (ETH, Zurich) for the organization of the donation of the original apparatuses. The encouragement and direct help of Gerardo Burton and Gustavo Arabethy (UBA, Buenos Aires), who also gave very important suggestions, is acknowledged. The support of the CEC through grant C11.0317.U also is acknowledged.
Using Communication Software to Capture Experimental Data Estel D. spraguel Thomas H. Ridgway University of Cincinnati Cincinnati. OH 45221
Many of the instmments used in our upper-level undergraduate lab courses are controlled by internal microprocessors, with no provision for storage of data on removable media. While these instruments provide ease of operation and convenient analysis of data for most standard procedures, it sometimes is desirable to treat the experimental data in ways not allowed for by the manufacturer. For example, the students in one of our senior lab courses carried out a kinetics experiment [recently described in this Journal (1311,which involves the flash photolysis of an organic dye. The thermal isomerization reaction occurring after the flash is followed bv monitorine the absorbance at a fixed wavelength as a Lnction of time. The expected functional dependence of the absorbance on time is A, =Aid + ( A , -A,, ) exp(-kt)
(1) where t is the time, A,, A. and A,F are the absorbance values a t times t, 0, and infinity, respectively, and k is the firsborder rate constant for the reaction. Because this exDression is nonlinear in one of the Darameters. k. a statistically appropriate analysis of the i a t a calls fir the use of model evaluation methods described earlier in this Journal (141, which make use of a nonlinear, least-squares program to fit the data to the appropriate expression. Since such procedures are unavailable in the spectrophotometer's software (Perkin-Elmer Lambda 4B), it is necessary to transfer the raw data to some other mi&owmputer 6 that the desired analysis can be carried out there. The most direct and obvious solution is to use the builtin functions of the spectrophotometer to print out the raw data, followed by manual entry into the other computer. This method clearly leaves much to be desired, both in the amount of labor required and in terms of the probability of introducing errors during the transcription process. Recently, we have been making use of a simpler method for instruments employing an RS-232 serial port for communication with an external ~rinter.The cable normallv con-
' Author to whom correspondence should be addressed Datastorm Technologies, Inc.
.,
neded to the serial port of the printer is connected to a manual switchbox instead, so that the output can be of a micnlrouted either to the printer or to the serial computer. With communication software (we use ProC o d ) running on the microcomputer, the software's log mode is turned on before instructing the spectrophotometer to ~ r i nout t the table of data. This automaticallvresults in the'data normally sent to the printer being cadtured to disk instead in the form of a standard ASCII fie. Since the data transfer rates are low, even the simplest personal comnuter is adeauate for this task. Once the data are on disk, it is a quick k d easy process for the student to import the ASCII tile into a s~readsheet.delete the extraneous table headings, etc., an'd arrange the data in the form required by the nonlinear, least-squares program. Transcription errors are eliminated, and large quantities of data are handled readily. In the abovekxample, the motivation for the data transfer is the need to make use of the nonlinear, least-squares program. The same situation exists whenever any &alysis tool only available outside the instrument must be employed.-other reasons may arise even more frequently, such as the need to prepare puhlication-quality figures from experimental data.
An Efficient FTlR Setup for the Undergraduate Teaching Laboratory Scott Hammond and Daniel A. ~ t r a u s ' San Jose State Univeffilty San Jose. CA 95192 We recently replaced three aging dispersion IR spectrometers in our undergraduate organic teaching laboratories with a single FTIR instrument. Because spectrometer time has been a frequent bottleneck in completion of lab exneriments. it was essential to confirmre our svstem to midimize the' time required for the &dent to obtain spectral data. With essentially no teaching-assistant support available, we also sought to minimize the instructor supervision needed. We found that use of a laser printer in conjunction with a programmable FTIR fulfills both of these requirements.' The hardware and software combination described herein instructs students step-by-stepin acauirine and lott tine a s~ectrumand allows them. without ihstru&or supervision, obtain an IR spectrum on preprinted chart paper with a separate peak list in an average student time of three minutes. To the best of our knowledge this is the first use of a laser printer with a teaching
FTIR instrument. With the price of laser printers coming down rapidly, the cost is not much greater than that of a good plotter. We are using a Perkin-Elmer 1620 FTIR and a Hewletb Packard LaserJet I11 ~ r i n t e er a u i ~ ~ with e d a Pacific Data Products plotter-in-;-cartridge plotter emulation card. The program (or "method") we have ~ r i t t e nUGLAB, ,~ is copied easily from disk to FTIR memory and is initiated by the instructor or a student bv ~ r e s s i n ethe "UGLAB" method soft key. It is not necessary to ree&er the program after each svectrum since the proeram is constructed as a continuous ioop with only twd choices at any poinh'proceed" or "stop." While in the program loop the remainder of the keypad is locked automatically.Routine operation is as follows. The screen instructs the student that an IR sample and chart paper are required and to press the "proceed" soR kev if they are available. Next the student is asked to verify that the sample compartment is empty for a background scan and to press "proceed" to acquire one. The background spectrum is displayed for two seconds. The student is then prompted to place a piece of preprinted chart paper in the manual feed chute of the laser printer and a sample in the beam and to press "proceednagain. A snectrum is acauired. disvlaved for 10 s. and Drinted on the &rt paper," &en a list dfpiak frequenkes and intensities is ~ r i n t e dautomaticallv on a sheet of lain Dauer from the paper feed tray of the laser printer. ~he'student is reminded to wait for both codes and is instructed how to clean the salt plates. The next student is prompted to press "Droceed" to rcstan the Droeram. 1f"sto~" isselected at any ];oint in the program, h e program is k t e d with plot pirameters set for printing with axes on unlined paper. This enables students wishing to obtain expanded plots or to use other features of the instrument in the manual mode of operation to print their spectral data with axes by simply pressing "plot" on the keypad. The use of a laser printer instead of a plotter saves considerable time. The printing of both spectrum and peak table for polystyrene as described above requires only 70 s. The entire program is run by an experienced operator in 100 s. By contrast an HP Color Pro plotter requires 2 min to plot a polystyrene spectrum with axes on plain paper and an additional 4 min to plot a peak table. There is no need to press any keys on the laser printer; whereas, pen selector and paper positioning keys must be selected on the plotter. Use of the FTIR program described reduces the number of FTIR keys that must be pressed from several to just one, avoiding confusion and delay. A
Literature Cited 1. Douglss. J.E. J. Chern. Edvc. 19W, 67,424. 2. Bordass, W. T:Linnett, J. W J. Cham. Edue 1910,47,765-168. 3. J J Cham Edue 1913,49,61&611. 4. Streifweiser, A., JI: Owens, P. H. Orbital and E k l m n Donsily Diogmms: Maemil-
OlconR.
,.,o... ."...,
L".
'Indicates author to whom correspondence should be addressed. %me required to plot FTiR data is normally the rate-limitingfactor in this technique. Perkins, W. D. J. Chem. Educ. 1987, 64, A269. 3~vailableas "UGLAB" on disk PC-4104 from project SERAPHIM, Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, WI 53706. Also provided on disk is documentation of hardware and softwareand a synthetic spectrum to facilitate calibration of the spectral printout to the pre-printed chart paper. 4Reproducibilityof paper placement using the manual feed chute on the HP LaserJet I i I is excellent, less than + 3 cm-' for the 1601 cm-' band of polystyrene. A79
Journal of Chemical Education
"".b
,072
5. Cooper, R;Casanova, J. J Chem. Educ 1991,GS. 4 8 1 4 8 .
6. Hanna, M . W Q u n t u m Mechoniesm Chamlstry; Benjamin: New Yark 1965, p200.
California.
11. V h a n VDM 620L TeIeType ContraUer Hsndbwk. Pvblieation No. 98 A9902 162 1971
12 \'anan lnrrrumcnt 0 1 ~ m n\TI . 16K 3 X R FT Pmmsm Lrr.ng% P a n Yo ~WIWVI.0Fcl 16. lv-3 13 H o ~ r . 5R Tay1or.C. .
