An ESEM short history and its future , already provided, may be sufficient for the general interest, whilst this web page could be redundant.  However, a public debate was initiated in 1996 in ESEM Related Posts from the Microscopy Listserver , which may raise some questions to those  delving deeper into the ESEM history (scroll down in the link to: From: Jim Darley: p&s-at-ultra.net.au. Date: Sat, 16 Nov 1996 17:37:00 +1100  Subject: Short History of ESEM (longish!) ).  The same original "posts" are mirrored herewith, in the event that the corresponding external link ceases to exist or is modified.  They  contain an initial attempt by Jim Darley (JD) to point out that the inventor of ESEM is Gerry Danilatos.  This was followed by a response by Vivian Robinson (VR) who claims the origins of ESEM for himself.  Up to the present time (April 2009), no response by Danilatos has been recorded on consideration that the keen reader could arrive at the correct conclusions based on a study of the technical literature furnished in the public domain.  Nevertheless, a significant confusion appears to persist as evidenced by contemporary literature, and so the missing (overdue) response by the third party (Danilatos) is contained herein below:

This constitutes a continuation in part of the ESEM history and events outlined in both previous Internet links above, in the context of which it is written.  Therefore, it is strongly recommended that the following text be read only after careful examination of the links provided above , in order to avoid unnecessary duplication and misinterpretation.

The comments made by JD in the "posts" are correct from the point of his understanding of what an ESEM is.  Along with the great majority of ESEM users, this technology was identified with the gaseous secondary electron detection, on which the commercial instrument was based.  It is undisputable that this detector (i.e. the use of an ionized gas as a detection medium) was invented by Danilatos in 1983 (but not initially patented).  The prior paper by Shah (MEATSEM, 1979, listed in the "posts") proposes the use of the "specimen current" as the detection mode, whilst the gaseous ionization products are considered detrimental to the formation of a clear image!  Therefore, VR claiming Shah as prior art is misleading.  JD has misquoted the number of Danilatos papers along with his age, probably in his enthusiasm to expound some extraordinary points of history.  He should have said "scores of papers" instead of "100" but this and the actual age of Danilatos should not add any substance to the rebuttal waged by VR on the true story of ESEM.

To come to a common understanding in this discussion, we have to define some terms of reference as to what constitutes an ESEM.  This is not just what the first manufacturer's interests wanted it to be, namely, ESEM= GSED (gaseous secondary electron detector).  Danilatos has defined the ESEM as a SEM capable of allowing at least 4.6 Torr (about >600 Pa) water vapor pressure, which is the pressure required to maintain the liquid phase of water at the freezing point of temperature, regardless of detection mode used.  VR should be satisfied with this definition as it allows him to have touched the ESEM history on account of his 1974 paper.  However, he was not the first worker in the field of ESEM because he was preceded in 1970 by:

Lane, W.C. (1970) The environmental control stage. Scanning Electron Microsc.: 43-48.

Lane first published liquid water images by alternative means.  The problem was that neither of those workers produced a system stable enough for routine production and operation of a commercial instrument.  This is evidenced by the fact that neither of those systems has ever been manufactured, nor will it ever be.  The reasons have been amply explained in the literature put out by Danilatos starting from 1979.  This will become more clear by examining some further details of the history below.

VR's response to JD, in turn, becomes not credible by his very opening paragraph stating that "They (implying ESEM type instruments) were introduced commercially by ISI/Akashi in conjunction with ETP Semra in 1978. To the best of my knowledge, these references predate all other references. It is this work which has resulted in some 2,000 of these types of SEMs being sold, out selling ESEM by a factor of about 10" .  Compare those words with a further statement by VR that " In 1978, the scientific work was extended to 5 torr and commercialization of the product to 2 torr had already occurred. Those represent a minimum of four and almost five orders of magnitude increase in available pressure in a SEM specimen chamber. Danilatos worked with me to extend this to 50 torr, an increase of only one order of magnitude. He worked with ElectroScan to increase the commercial limit to 20 torr, again an increase of only one order of magnitude over ISI/Akashi's 2 torr in 1978 ".  It seems the difference from 2 to 5 Torr is of no importance to VR, nor presumably to the users of his ETP Semra attachments.  There is also an implied no difference to ISI-SEMRA-WET-SEM either, despite the fact that no wet specimen is physically possible to exist at 2 Torr.  An attempt is made below to restore the truth as far as is practical.

Like above, it is VR's favorite way to measure his progress in terms of orders of magnitude (on a logarithmic scale) for the pressure used - see also: " They operated at pressures up to 2 torr, almost 5 orders of magnitude above the previous specimen chamber limit of 10exp-4 torr "  However, the real importance lies in the exponential decay of the electron beam with linear increase of pressure and not on the logarithmic scale of pressure used by VR.  It is the logarithm of the beam intensity that depends linearly on the pressure.  That is, the beam decreases by exp(-kp) so that the percentage loss in going from p= 2 to p= 5 Torr is greater than the percentage loss in going from p= 0 to p= 2 Torr (the latter pressure limit constituting the claim of his commercial endeavors).  This means that it is much more difficult to operate the ESEM at 5 Torr than at 2 Torr, although using the "Robinson scale" the difference appears to be marginal, i.e. if measured in orders of magnitude of pressure.  The unsuspecting (or uncritical) reader should be aware of the actual practical difference between 2 and 5 Torr.  (Actually, considering that someone (like VR) could also claim 7 orders of magnitude (10000000X) more than the meagre 1 order of 10X by Danilatos, if one used a better specimen chamber vacuum at E-6 Torr (even lower), it is amazing that such a reasoning has persisted for so long so prominently in scientific forums). 

In short, the significance in achieving satisfactory imaging by increasing the pressure from 2 to 5 Torr lies not only in overcoming the exponential loss of beam electrons but also in being able to image water in its liquid phase, routinely.  Likewise, by achieving 20 Torr signifies also the operation at room temperature with aqueous specimens (without the need of a cooling device), whilst 47 Torr is the pressure at human body temperature and 760 Torr is the ambient pressure (no specimen chamber).  Danilatos has successfully imaged and published results with his ESEM and ASEM in the entire range of those pressures.

In the "post", VR extensively refers to a joint Danilatos and Robinson (1979) paper, in which the ESEM is reported to operate successfully at >50 Torr (about 7000 Pa) and at room temperature.  He states that this is the limit of upper pressure operation for ESEM (in opposition to the Danilatos atmospheric limit).  Thus, he clearly supports the ESEM operation up to this (i.e. allegedly "his") alleged limit.  However, this leaves unexplained the fact that his company had sold 2000 units none of which exceeded 2 Torr!  None of his commercial instruments has ever achieved even 5 Torr based on his claim (" scientific work ") of 1974!  How can one reconcile these gross contradictions within the same "post"?  If practice is the criterion of truth, then one needs to go no further.

Referring again to that joint paper and in the overall context of remarks by VR, there seems to be an attempt by VR to appear as the prime mover and contributor behind all progress in ESEM at that time, an attempt to explain "who did what", despite his words of work " done together".  It is generally customary and acceptable to add a "supervisor" as coauthor even if only by virtue of initiating a project, and there should be no subsequent attempt by either author to quantify the importance of each party following publication of a joint paper, other than the order of authors' names.  Unfortunately, the stance of this coauthor demands an appropriate response that should complement the background events and VR's misrepresentations in the "post":

After completion of his Ph.D. in 1977, in a different field, Danilatos started work with VR on January 2, 1978, under an ARGC grant obtained by VR, for the purpose of examining wet biological specimens.  At the outset, VR demonstrated literally the "fluking" (to quote him) of wet images of wool fibers, which had to be taken quickly before the electron beam was cut off due to severe gas leakage into the gun chamber, and whilst the entire microscope was splashed with liquid nitrogen to lower the saturation water vapor pressure, for an hour or so prior to commencement of any imaging.   VR went away promoting his BSE detector , leaving Danilatos alone.  This was the state of progress since VR published his 1974 paper, so that one may wonder what was the progress in the interim four years.  Within a month from his employment, Danilatos transferred to the SEM his temperature control device used during his prior Ph.D. years from the other field, fixed various leaks, used a thin BSE detector and was able to routinely obtain imaging  around 5 Torr.  Shortly afterwards, he disposed of the temperature control device entirely, as he was able to operate routinely at room temperature, at very high pressures in excess of 50 Torr.  However, this exceeded his brief and instructions by VR, namely, those being the operation only at the freezing point.  At the request of VR, School Management asked Danilatos to resign well before the end of ARGC term.  Astonishingly, Danilatos' task being over and above than complete, he was asked to go, in no uncertain terms, instead of being commended or promoted.  Danilatos protested strongly with the School authorities and, in a meeting with senior staff, it was decided that Danilatos should continue his successful work "as he saw fit, but he will take the brunt of his failure or the credit of his success, accordingly".  At that point, the short-lived Danilatos-Robinson collaboration was effectively dead, existing only as a formality until the ARGC Grant expired.  It was under those circumstances that the joint Danilatos-Robinson (1979) paper was published.   

It is important to note that this joint paper contains an experimental analysis of the JSM2, which contradicts some prior claims made by Robinson. For example, from Fig. 1 and 2 of that paper, it is shown that the oil diffusion pump at the electron gun stalls and breaks the vacuum required for the gun when 21 torr (=28 mbar) is maintained in the specimen chamber.  Therefore, the image of the ant eye furnished by Robinson in 1976 [Scanning electron microscope environmental cells. Scanning Electron Microscopy/I:91-100 ] was a sheer impossibility to reproduce at 21 torr in the same "wet stage modification" in 1978.  Even at 10 torr (previously claimed, but without any image shown, to be the upper limit of the system) it was practically impossible to operate the system due, in addition, to the serious electron beam losses in the column just prior to the stalling of the diffusion pump at the gun.  However, at the beginning of 1978, it was possible to obtain one image at a time at the freezing point, just by "fluke", shortly before the instrument operation was cuff-off and had to be restarted again.  This was probably due to the fact that the nominal 100 micron aperture was in fact much larger, like around 136 micron (as was found from the available packet of nominally 100 micron apertures that was used in the "joint" paper). For this reason, the characteristic (dashed line) in Fig. 2 for a 100 micron was a calculated one.  Therefore, the fact remains that for 4 years from 1974 to 1978 when Danilatos took over the work, the "wet stage modification" had remained stagnant and unstable.  The dramatic improvements coincide only with Danilatos coming on-board the ESEM development from January 1978.

Danilatos also published the results of the ARGC work on fresh or living plant material (1981) alone, because Robinson refused to appear as coauthor.  In the same period, Danilatos first introduced the new term ESEM (see in text) in 1979, he also submitted a joint authorship paper at a wool conference ( Danilatos-Robinson-Postle), whereby Danilatos insisted on the introduction of the new ESEM term despite strong opposition by Robinson, who was then promoting the alternative terms " Environmental Cell Modifications (ECM ) quickly followed by Charge Free Anti-contamination Systems (CFAS) and WET-SEM" for his commercial  accessories (by his own admission in the posts!).  Noteworthy is also the publication:

Robinson VNE (1978). The SEM examination of wet specimens, Scanning Vol. 1, 149-156 ,

which was submitted in July 24, 1978 and published the same year by the then new journal Scanning.  This paper was sent to the publisher while Danilatos had already greatly advanced the ESEM to operate at high pressure and room temperature, yielding high quality micrographs, but no mention of his name appears anywhere in that paper.  This and another paper at that time by

Robinson VNE (1980). Imaging with backscattered electrons in a scanning electron microscope, Vol. 3, 15-26 (submitted in July 1979)

clearly established the "pressure limits" of any future claims by Robinson, i.e. no other than operation at the freezing point exclusively using a single aperture and his plastic BSE detector, which proved inadequate and unsuitable for effective ESEM work, as shown by

Danilatos, G.D. (1985) Design and construction of an atmospheric or environmental SEM (part 3) . Scanning 7:26-42

The addition of the second aperture, in particular, was not simply necessitated by Danilatos' atmospheric SEM (per VR assertion) but initially by electron optical considerations, because the single aperture used by VR prevented the approach of the specimen close to it and hence prevented the raising of the pressure to any significant level.  In fact, there is no additional pumping between the two apertures in the joint 1979 paper, where it is demonstrated how the imaging problems arising from the single aperture were overcome by the addition of a second aperture.  This critical breakthrough was achieved by Danilatos alone.  At that time, Danilatos also invented the atmospheric SEM (ASEM) which he patented with the University of NSW (Unisearch Ltd.). The patenting was allowed only after (i.e. half year later) Danilatos could demonstrate it experimentally following strong opposition (negative advice) by Robinson to Unisearch applying for a patent.  Later, this patent earned royalties of over a million dollars to the University of NSW.  The above events should explain, perhaps, why VR did not use commercially "his" alleged high pressure achievements up to 50 Torr, probably in consequence of his public and private opposition to the Danilatos ESEM and ASEM (an opposition well established with his peers and the university authorities during those years).   

It is unfortunate that in the "posts" 16 years later (in 1996), VR returns to lay claim of the "fatherhood" of ESEM.  His opposition to ESEM never having abated, it is absurd that he disregards the true history of creation of a new industry of microscopy as well as the advancement of a sophisticated science and practice, over and above what the industry has achieved.  Still to this day (April 2009) neither VR nor his associated companies have come out with any ESEM operating at 20, or even 5 Torr, let alone 50 Torr. That is because the only way to effectively achieve these goals is only by implementation and acknowledgement of the Danilatos scientific works in every respect, from optimizing the differential pumping system to the SE and BSE detection, and beyond. 

In the "posts", there are other references to certain events mixed-up around, but the reader may easily weed them out on the evidence furnished so far.  More details will be added later.  The story will not be complete until and unless many more "inside" events that led to the relocation (or dislocation) of ESEM from the University grounds, its further tribulations later at CSIRO and then at ElectroScan Corporation and some misconceptions in the scientific community are all spelled out and documented.  In fact, the ESEM story goes far beyond the early differences between two workers.  Far greater opposition to ESEM developments has come from "external" or unexpected quarters.  The story is indeed long and tortuous, the evidence voluminous, and can only be published by installments as the opportunities arise.

A separate technical survey on the real workings of prior use of gas in a SEM will further support the statements of the present response and establish the real history of the early years of ESEM on unshakable scientific grounds.  

Jim Darley, who initiated this discussion, must have, after all, truly sensed the pitfalls haunting science and technology worldwide.  It is hoped that this exposition restores historical truth and contributes towards bettering science and technology elsewhere, in the future.