Microscopy and Unknown Means
I’m a sucker for those fiction CSI books written by the professionals in the field. Naturally I’m drawn to Elizabeth Becka’s writing. Her forensic specially isn’t detailed on the book jacket but I suspect it’s trace evidence based on her website (www.elizabethbecka.com) and her writing. That’s important because it means microscopy. Equally interesting is that she worked for the coroner’s office in Cleveland, Ohio. That’s two connections to MSNO.
I recently picked up her book “Unknown Means”. Let’s look at the microscopy in it.
The first example that caught my eyes was not microscopy, but microsample IR analysis. I’m including this because it’s was a small sample and I have a weakness for IR spectroscopy. Evelyn, our heroine, nicely explains how organic functional groups absorbing specific radiation producing a nice color spectrum of each compound. I liked the image of a color spectrum but I fail to understand why a spectrum of non-visible light would require a color printer. I guess since I take photos graphs of very small objects I should us a tiny, tiny printer. Evelyn identifies oily stuff as silicone by the wide peak at 1000cm-1. Silicone oil does have a wide peak around 1000cm-1 (assuming it is polydimethylsilioxane), but I’d call it a double peak. Our heroine dismisses (rightly so) the common nature of silicone. My friends in IR spectroscopy claim the earth has a mono-molecular layer of silicone. It’s been my experience they maybe right. Evelyn wrongly attributes it to being the most common metal on earth. Silicon is the element and metal (Okay, metalloid) and is transparent to IR radiation. Silicone is the polymeric organic material.
This is not a good sign. A microscopist should know the difference between an element and a compound. I’ll assume the editor chopped out the information to streamline the story.
All is not lost, later she uses polarized light microscopy to identify a fiber as nylon mounted in Permount. That’s a good catch. I would have used Aroclor 166, but I’m a dinosaur. With a little more work she could have distinguished between nylon 6-6 and nylon 6, but that would only distracted from the story.
A few pages later Evelyn tells us how little information she was able to gleam from a dry mount of an unknown. This demonstrates the difference between a dry mount and the previously prepped nylon fiber in a mounting media. The refractive index of air is 1 and just about everything has a refractive index significantly larger than 1.
You would expect way too much contrast and glare, even with the sub-stage iris fully open, to see the fine morphology. Still I understand her dilemma: mount it in a solvent and the material could dissolve or react. I recently had a co-worker examined lithium oxide in water. Good bye sample, hello hydroxide and carbonate. With the context provided by the story and Evelyn’s macro description, I’d try distilled water (N=1.33). This would lower the contrast and the unknown could be recovered by wicking the water away with a corner of a Kimwipe. Still, I count this as good microscopy.
To identify an unknown fiber, Evelyn uses standards to compare known materials to her unknown and discovers the fiber is a strand of hemp. I would have used a polarized light scope, but she gets by with a stereomicroscope. More good microscopy, but later she identifies a fiber she describes as “...straight and clear. Almost like hairs without the medullas.” as Kevlar. I’ve never seen clear Kevlar. There fibers always have a yellowish tint and are never clear. The refractive indexes of Kevlar, both perpendicular and parallel to the long dimension of the fiber are very high giving the fiber enormous birefringence. The center of a Kevlar fiber, seen in cross-polarized light, has a most medulla-like look caused by micro crystals and who could miss the characteristic “X” and “Y” cracking observed in the fiber? Clearly, a microscopy miss. Sorry Evelyn.
Read the book yourself. It’s a great story which uses realistic microscopy to help solve a series of crimes, written by someone who actually does it. What could be better?
As for me, well I’m simply jealousy of both the word-smithing Ms. Becka does as well as the microscopy. PLM, SEM-EDS and IR Spectroscopy. It doesn’t get any better than these three..
PS: I’ve always wanted to spoil a story, so the killer is, ….What are you doing here? No - stop! Put that down! No! Not the eeeeeeeeeeeeeeeeeeeeeeeee
I recently picked up her book “Unknown Means”. Let’s look at the microscopy in it.
The first example that caught my eyes was not microscopy, but microsample IR analysis. I’m including this because it’s was a small sample and I have a weakness for IR spectroscopy. Evelyn, our heroine, nicely explains how organic functional groups absorbing specific radiation producing a nice color spectrum of each compound. I liked the image of a color spectrum but I fail to understand why a spectrum of non-visible light would require a color printer. I guess since I take photos graphs of very small objects I should us a tiny, tiny printer. Evelyn identifies oily stuff as silicone by the wide peak at 1000cm-1. Silicone oil does have a wide peak around 1000cm-1 (assuming it is polydimethylsilioxane), but I’d call it a double peak. Our heroine dismisses (rightly so) the common nature of silicone. My friends in IR spectroscopy claim the earth has a mono-molecular layer of silicone. It’s been my experience they maybe right. Evelyn wrongly attributes it to being the most common metal on earth. Silicon is the element and metal (Okay, metalloid) and is transparent to IR radiation. Silicone is the polymeric organic material.
This is not a good sign. A microscopist should know the difference between an element and a compound. I’ll assume the editor chopped out the information to streamline the story.
All is not lost, later she uses polarized light microscopy to identify a fiber as nylon mounted in Permount. That’s a good catch. I would have used Aroclor 166, but I’m a dinosaur. With a little more work she could have distinguished between nylon 6-6 and nylon 6, but that would only distracted from the story.
A few pages later Evelyn tells us how little information she was able to gleam from a dry mount of an unknown. This demonstrates the difference between a dry mount and the previously prepped nylon fiber in a mounting media. The refractive index of air is 1 and just about everything has a refractive index significantly larger than 1.
You would expect way too much contrast and glare, even with the sub-stage iris fully open, to see the fine morphology. Still I understand her dilemma: mount it in a solvent and the material could dissolve or react. I recently had a co-worker examined lithium oxide in water. Good bye sample, hello hydroxide and carbonate. With the context provided by the story and Evelyn’s macro description, I’d try distilled water (N=1.33). This would lower the contrast and the unknown could be recovered by wicking the water away with a corner of a Kimwipe. Still, I count this as good microscopy.
To identify an unknown fiber, Evelyn uses standards to compare known materials to her unknown and discovers the fiber is a strand of hemp. I would have used a polarized light scope, but she gets by with a stereomicroscope. More good microscopy, but later she identifies a fiber she describes as “...straight and clear. Almost like hairs without the medullas.” as Kevlar. I’ve never seen clear Kevlar. There fibers always have a yellowish tint and are never clear. The refractive indexes of Kevlar, both perpendicular and parallel to the long dimension of the fiber are very high giving the fiber enormous birefringence. The center of a Kevlar fiber, seen in cross-polarized light, has a most medulla-like look caused by micro crystals and who could miss the characteristic “X” and “Y” cracking observed in the fiber? Clearly, a microscopy miss. Sorry Evelyn.
Read the book yourself. It’s a great story which uses realistic microscopy to help solve a series of crimes, written by someone who actually does it. What could be better?
As for me, well I’m simply jealousy of both the word-smithing Ms. Becka does as well as the microscopy. PLM, SEM-EDS and IR Spectroscopy. It doesn’t get any better than these three..
PS: I’ve always wanted to spoil a story, so the killer is, ….What are you doing here? No - stop! Put that down! No! Not the eeeeeeeeeeeeeeeeeeeeeeeee
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